April 12 – The Baltimore Orioles dismiss manager Cal Ripken after their sixth consecutive loss starting the season. Ripken is replaced by Frank Robinson who will see the streak extended to a Major League-record 21 consecutive losses.
April 29 – The Baltimore Oriolesshut out the Chicago White Sox, 9–0, at Comiskey Park. It is the first victory of the season for the helpless Orioles, behind a strong pitching effort by starter Mark Williamson, who was credited with the win after allowing three hits on two strikeouts and no walks in six innings of work. Closer Dave Schmidt earned the save, giving up one hit on one strikeout and no walks in three innings. For the Orioles, Cal Ripken, Jr. went 4-for-5 with three runs and one RBI, including a double and a home run, while Eddie Murray hit a two-run homer. Jack McDowell was the losing pitcher. Baltimore is now 1-21.
April 30 – Cincinnati Reds manager Pete Rose shoves umpireDave Pallone twice after a delayed call by Pallone at first base results in the New York Mets scoring the go-ahead run and the argument between Rose and Pallone escalates to the shovings when Pallone allegedly touched Rose under his eye pointing back at him. Three days later, National League president A. Bartlett Giamatti suspends Rose for 30 days, the longest such suspension for an on-field incident by a manager in MLB history.
August 9 – The Chicago Cubs won the first official night game at Wrigley Field by beating the New York Mets 6–4. The lights had been turned on just before the start of the prior night's game, but that game was rained out.
September 20 – Wade Boggs becomes the first player in Major League history, since 1901, to collect 200 or more hits in six consecutive years. He is also the second player (to Lou Gehrig) to collect 200 hits and 100 bases on balls in three straight seasons.
September 28 – One of the great season closing games in history is played as Orel Hershiser of the Los Angeles Dodgers and Andy Hawkins of the San Diego Padres each pitch ten scoreless innings. The Padres eventually win, but the tenth inning proves to be Hershiser's 59th consecutive scoreless inning, breaking Don Drysdale's record streak of 58 consecutive innings.
October 15 – In Game One of the 1988 World Series at Dodger Stadium, the Los Angeles Dodgers trail the Oakland Athletics, 4–3, in the bottom of the ninth inning when the Dodgers' Kirk Gibson, badly injured in the NLCS against the New York Mets, hobbles to the plate to pinch-hit against Oakland's lethal closer, Dennis Eckersley. With two outs, a 3-2 count against him, and Mike Davis on second base, Gibson uses his upper body and wrists to launch a backdoor slider from Eckersley into the right-field stands for a 5–4 Los Angeles victory. Gibson's home run re-energized the underdog Dodgers and shattered the confidence of the A's, who lost the series in five games. It inspired the coining of the phrase "walk-off home run", and is widely regarded as one of the greatest moments in baseball history.
October 20 – Los Angeles Dodgers pitcher Orel Hershiser ends his dream season with a 5–2 four-hitter over the Oakland Athletics in Game Five of the World Series. The win gives the Dodgers their first World Championship since 1981, and makes them the only team to win more than one World Series in the 1980s. Hershiser is selected the Series MVP.
November 10 – Los Angeles Dodgers pitcher Orel Hershiser, who posted a 23-8 record with 178 strikeouts and a 2.31 ERA, is a unanimous choice as National League Cy Young Award winner. Hershiser becomes the ninth pitcher in National League history to win the award unanimously, after receiving all twenty-four first place votes from the BBWAA.
November 28 – Rich Gedman becomes the highest paid catcher in American League history when he signs a one-year contract with the Boston Red Sox for $1.2 million.
December 14 – CBS paid approximately US$1.8 billion for exclusive over-the-air television rights for over four years (beginning in 1990). CBS paid about $265 million each year for the World Series, League Championship Series, All-Star Game, and the Saturday Game of the Week. CBS replaced ABC (which had broadcast Monday and later Thursday night baseball games from 1976 to 1989) and NBC (which had broadcast Major League Baseball in some shape or form since 1947 and the Game of the Week exclusively since 1966) as the national broadcast network television home of Major League Baseball. It was one of the largest agreements (to date) between the sport of baseball and the business of broadcasting. The cost of the deal between CBS and Major League Baseball was about 25% more than in the previous television contract with ABC and NBC. The deal with CBS was also intended to pay each team (26 in 1990 and then, 28 by 1993) $10 million a year.
February 1 – Red Phillips, 79, relief pitcher who posted a 4-4 record in 29 games for the Detroit Tigers in the 1934 and 1936 seasons.
February 3 – Jocko Thompson, 71, pitcher for the Philadelphia Phillies in four seasons, also a much-decorated American lieutenant who served in the European Theater during World War II.
February 16 – Bill Cox, 74, pitcher in 50 games for the St. Louis Cardinals, Chicago White Sox and St. Louis Browns from 1936 to 1940, who later served in Germany in the U.S. Army during World War II.
February 20 – Bob O'Farrell, 91, catcher for four National League teams over 21 seasons who won the 1926 MVP award with the St. Louis Cardinals.
February 23 – Pete Donohue, 87, pitcher who had three 20-win seasons for the Cincinnati Reds and beat the Philadelphia Phillies 20 consecutive times from 1922–1925.
February 26 – Tom Oliver, 85, fine defensive center fielder for the Boston Red Sox in the early 1930s.
February 28 – Harvey Kuenn, 57, eight-time All-Star shortstop and outfielder, most notably with the Detroit Tigers, who batted .303 lifetime and led the American League in hits four times and doubles three times, while winning the 1953 Rookie of the Year Award and the 1959 batting title, and also managing the Milwaukee Brewers to their first pennant in 1982,
March 6 – Lou Legett, 86, catcher for the Boston Red Sox between 1929 and 1935.
March 6 – Dick Ricketts, 54, pitcher for the 1959 St. Louis Cardinals and also a forward-center in NBA with the St. Louis Hawks and the Rochester/Cincinnati Royals from 1955–1958.
March 11 – Art Daney [Chief Whitehorn], 84, Native American of the Choctaw Nation of Oklahoma, who pitched briefly for the 1928 Philadelphia Athletics
March 14 – Zeb Terry, 96, shortstop/second baseman who hit .260 in 589 games for the Boston Braves, Chicago Cubs, Chicago White Sox and Pittsburgh Pirates from 1916 to 1922.
March 16 – Jigger Statz, 90, outfielder for the New York Giants, Boston Red Sox, Chicago Cubs and Brooklyn Robins from 1919 to 1928, who hit .319 for the 1923 Cubs including 209 hits, 110 runs, 51 extrabases, 70 RBI and 29 stolen bases.
March 21 – Edd Roush, 94, Hall of Fame center fielder for the Cincinnati Reds who batted .323 lifetime, leading the National League in batting twice and in slugging, doubles and triples once each, while hitting 30 inside-the-park home runs and ending with 182 triples for the 13th-most triples in major league history.
March 29 – Ted Kluszewski, 63, All-Star first baseman who played from 1947 through 1961 for four teams, most prominently with the Cincinnati Reds, who led the National League with 49 home runs and 141 RBI in 1954 and batted .300 seven times, also known for his sleeveless jersey, and later a Reds coach.
April 4 – Jack Aragón, 72, a 12-season catcher and manager in the minor leagues who appeared in one game for the 1941 New York Giants.
April 4 – Charlie Snell, 94, backup catcher who hit .211 in eight games for the 1912 St. Louis Browns.
April 5 – Tom Earley, 71, relief pitcher who posted an 18-24 record with a 3.78 ERA for the Boston Braves from 1938 to 1945.
April 9 – Syd Cohen, 81, pitcher for the Washington Senators from 1934 to 1937, and later a minor league baseball manager.
April 12 – Frank Skaff, 77, first baseman for the 1935 Brooklyn Dodgers and the 1943 Philadelphia Athletics, who later managed the 1966 Detroit Tigers.
April 14 – Ralph Winegarner, 78, infielder/outfielder/pitcher for the Cleveland Indians and St. Louis Browns in parts of six seasons spanning 1930–1949.
April 22 – Len Church, 46, relief pitcher for the 1966 Chicago Cubs.
April 27 – Tommy Thomas, 88, pitcher who won 117 games for the Chicago White Sox, Washington Senators, Philadelphia Phillies, St. Louis Browns and Boston Red Sox from 1926 through 1937.
April 29 – Dom Dallessandro, 74, outfielder for the Boston Red Sox and Chicago Cubs in eight seasons from 1937–1947, who posted a .304 average and a .400 on-base percentage in 1944, while missing the 1945 Cubs' pennant-winning season and a chance to play in the 1945 World Series due to military service during World War II.
July 1 – Ed Sauer, 69, outfielder who played in the 1940s with the Chicago Cubs, St. Louis Cardinals and Boston Braves.
July 2 – Tom Drake, 75, relief pitcher for the Cleveland Indians and Brooklyn Dodgers from 1939 to 1941.
July 4 – Lee Weyer, 51, National League umpire since 1963 who worked in four World Series and five NL Championship Series.
July 8 – Frank Ellerbe, 84, third baseman who hit .268 in 420 games for the Senators, Browns and Indians from 1919 to 1924.
July 10 – Ernie Nevel, 69, relief pitcher who appeared in 14 games with the New York Yankees and Cincinnati Reds from 1950–1953.
July 14 – Whitey Witt, 92, outfielder who hit .287 with 18 home runs and 302 RBI in 1139 games for the Athletics, Yankees and Robins from 1916 to 1926; the last surviving member of the 1923 New York Yankees World Series champions.
July 15 – Clyde Beck, 88, infielder for the Chicago Cubs and Cincinnati Reds from 1926 to 1931.
July 20 – John W. Galbreath, 90, owner of the Pittsburgh Pirates from 1945 to 1985, during which period the team won three World Series.
July 23 – Ken Polivka, 67, relief pitcher who appeared in two games with the 1947 Cincinnati Reds.
July 24 – Jerry Lane, 62, pitcher for the Senators and Reds from 1953–1955.
July 24 – Joe Orengo, 73, valuable man at all four infield positions, who hit .238 in 366 games for the Cardinals, Giants, Dodgers, Tigers and White Sox between 1939 and 1945.
July 26 – Al Flair, 62, first baseman for the 1941 Boston Red Sox.
August 2 – Bob Berman, 89, backup catcher for the 1918 Washington Senators.
August 5 – Ralph Michaels, 86, backup infielder who hit .295 in 32 games for the Cubs from 1924–1926.
August 13 – Mel Almada, 75, outfielder who hit .284 from 1933 through 1939 for the Boston Red Sox, Washington Senators, St. Louis Browns and Brooklyn Dodgers, who is regarded as the first Mexican player to appear in a major league baseball game.
August 22 – Bob Daughters, 74, played for the 1937 Boston Red Sox.
October 6 – Bob Boken, 80, infielder for the Washington Senators and Chicago White Sox from 1933 to 1934.
October 8 – Boob Fowler, 87, infielder who hit .326 in 78 games for the Cincinnati Reds and Boston Red Sox from 1923 through 1926.
October 14 – Abie Hood, 85, second baseman who hit .286 in five games for the 1925 Boston Braves.
October 14 – Vic Raschi, 69, All-Star pitcher who won 20 games for the Yankees in three straight years (1949–51), including World Series clinchers in 1949 and 1951.
October 19 – Bill Burgo, 67, backup outfielder for the Philadelphia Athletics in the 1943 and 1944 seasons
October 21 – Regino 'Reggie' Otero, 73, Cuban first baseman who had a long minor league career (1936–1953), played briefly with the 1945 Chicago Cubs, also played 13 years in the Cuban League, and later enjoyed a successful career as a manager in the Cuban, Mexican and Venezuelan leagues
October 27 – Ben Steiner, 67, second baseman for the Boston Red Sox and Detroit Tigers from 1945 to 1947
October 28 – Dave Tyriver, 50, pitcher for the 1962 Cleveland Indians.
October 29 – Andy Cohen, 84, second baseman who hit .281 in 262 games with the New York Giants from 1926–29.
October 30 – Bernie Walter, 80, pitcher for the 1930 Pittsburgh Pirates.
November 1 – Lefty Sullivan, 72, pitcher for the 1939 Cleveland Indians.
November 5 – Glenn Chapman, 82, infielder who hit .280 in 67 games for the 1934 Brooklyn Dodgers.
November 9 – Bob Weiland, 82, pitcher who won 62 games with the White Sox, Red Sox, Indians and Browns from 1928 to 1940.
November 21 – Carl Hubbell, 85, Hall of Fame pitcher who won 253 games for the New York Giants, second most among NL left-handers upon retirement; named NL's MVP in 1933 and 1936, he led league in wins and ERA three times each and had 1.79 ERA in six World Series starts; 1677 strikeouts were NL record for left-handers until 1958, and won 24 straight games in 1936-37.
November 22 – Ray Kelly, 74, sportswriter who covered the Philadelphia Athletics and Phillies since the late 1940s.
November 30 – Wally Berger, 83, All-Star center fielder for the Boston Braves who had four 100-RBI seasons, batted .300 lifetime; led NL in homers and RBI in 1935.
December 12 – Joe Reichler, 73, sportswriter and author who wrote for the Associated Press for 20 years and served as an assistant to the commissioner after 1966; editor of the Macmillan Baseball Encyclopedia since its first edition in 1969.
December 16 – Bob Kahle, 73, pinch-hitter for the 1938 Boston Braves.
December 21 – Willie Kamm, 88, third baseman for the White Sox and Indians who led AL in fielding average eight times and in putouts seven times; batted .308 in 1928 and led league in walks in 1925.
December 29 – John Happenny, 87, backup infielder who hit .221 in 32 games for the 1923 Chicago White Sox.
December 29 – Earl Mossor, 63, pitcher who appeared in three games with the 1951 Brooklyn Dodgers.
December 31 – Wes Flowers, 75, relief pitcher who posted a 2-2 record with a 5.40 ERA for the Brooklyn Dodgers in 1940 and 1944, and later served in the Navy during World War II.