Major professional tennis tournaments before the Open Era
Before the beginning of the Open era in April 1968, only amateurs were allowed to compete in established tennis tournaments, including the four Grand Slams. There was no prize money and players were compensated for travel expenses only. This changed with the advent of the Open era. However many top tennis players turned professional to play legally for prize money in the years before the open era. They played in separate professional events, mostly on tours involving head-to-head competition, but also in professional tournaments as the biggest events on the pro tour.
 Professional Majors
In addition to the head-to-head tours, there were the annual professional tournaments called Championship tournaments, where the world's top professional players played. These tournaments held with a certain tradition and longevity.
The oldest of these three Professional Majors, or "Professional Grand Slams", was the U.S. Pro Tennis Championships, played at a variety of different venues and on a variety of different surfaces, between 1927 and 1999. Between 1954 and 1962, the US Pro was played indoors in Cleveland and was called the World Professional Championships. The most prestigious of the three was generally the Wembley Championship. Played between 1934 and 1990, at the Wembley Arena in England, it was unofficially usually considered the world's championship until 1967. The third professional major was the French Pro Championship, played between 1934 and 1968, on the clay-courts of Roland Garros, apart from 1963–1967, when it was played on the indoor wood courts of Stade Coubertin.
 U.S. Pro Tennis Championships
The U.S. Pro Tennis Championship, also known as the US Pro, was an annual tournament, later known as MFS Pro Championships. It was first organized by player Vinny Richards when promoter C. C. Pyle withdrew interest in the project. It was first played on the Notlek courts located at 119th Street and Riverside Drive, Manhattan. The tournament was held at various locations in several states until 1964, when it moved to the Longwood Cricket Club in Chestnut Hill, Massachusetts.
 French Pro Championship
The French Pro Championship was first held in 1930, held by the "Association Française des Professeurs de Tennis (AFPT)", entitled "Championnat International de France Professionnel" (French Pro Championships) in June, 18-22, 1930. From 1930 the French Pro Championship was always played at Paris, on outdoor clay at Roland Garros except from 1963 to 1967 where it was held at Stade Pierre de Coubertin on indoor wood.
 Wembley Championship
The Wembley Championship, also known as the Wembley Pro, was held at the Wembley Arena, in London. This professional event ran from 1934–1967 and was originally played on a wood surface placed over the top of a drained pool. It was officially known as the "London Indoor Professional Championships" from 1951 through 1967.
 List of Professional Grand Slam Champions
The status of the 1933 French Pro is unclear. In History of the Pro Tennis Wars, by Ray Bowers, there is no mention of a French Pro tournament in 1933. The only professional competition played that year at Roland Garros was a USA-France meeting, September 22–24, in the Davis Cup format. Many sources probably wrongly considered the Tilden-Cochet match as a final of a supposed French Pro.
The status of the Wembley Championships of 1936 and 1938 is unclear. Two of the three major sources for the professional championships list the results as shown. Ray Bowers' History of professional tennis says that neither of these tournaments ever occurred and offers substantiating evidence for his assertion.
The 1937 US Pro was the first pro event open to amateur players and is considered as both the U.S. Pro Tennis Championship and first "true" U.S. Open event.
The US Pro events from 1950–1962, were billed the World Pro Championship with the exception of 1951, where a separate US Pro (at Forest Hills) and World Pro (in Cleveland) were held.
The status of 1953 "French Pro" is unclear. Joe McCauley included this tournament in his list of French Pro tournaments but he prefaced in his book "History of Professional Tennis" that it may not have been considered at the time as an official French Pro.
 Other important tournaments
The Championships at Wimbledon, the US Championships, the French Championships, and the Australian Championships were typically the top events, where amateur players could compete for the title, albeit without prize money. Since the professional circuit was less organized and somewhat less popular than the amateur circuit, the professional events hierarchy changed each year. In 1934 the US Pro was a high-class tournament with all top ranked pro players whereas in 1936 it was a meeting between pro teachers without any leading pro players. A tournament could even be canceled at any time due to poor attendance.
Consequently for a given year a pro tournament was important when it attracted the best pro players and then another year this same tournament could be a second-rank tournament because few or no leading players came. Before the open era in addition to numerous small tournaments and head-to-head tours between the leading professionals, there were some major tournaments which stood out at different periods. Some survived sporadically because of financial collapses while others temporarily rose to the highest levels of competition when other tournaments weren't held. These include:
 Bristol Cup: 1920–1932
Sometimes labelled "Professional Championships of France" this tournament was held on the French Riviera at Menton, at Cannes.
List of Bristol Cup winners:
- 1920: Romeo Acquarone
- 1921: John C.S. Rendall
- 1922: John C.S. Rendall
- 1923: John C.S. Rendall
- 1924: Albert Burke
- 1925: Albert Burke
- 1926: Karel Koželuh
- 1928: Karel Koželuh
- 1929: Karel Koželuh
- 1930: Karel Koželuh
- 1931: Karel Koželuh
- 1932: Karel Koželuh
 Professional Championship of the World: 1927–1928
This event was held in October on Clay courts, at the Queen's Club in London. In 1928 Myers of the Daily Telegraph wrote that "this was the best pro tournament ever held in England."
List of Queen's Club Pro winners:
 World Pro Championship: 1932–1933
The World Pro Championship were held in 1932 and 1933 in Berlin at the Rot-Weiss club, on clay. It had a very large participation (over 80 players). According to Ray Bowers in the History of the Pro Tennis Wars Chapter IV (cited lower down), this tournament at the time was regarded as the most prestigious professional tournament in the world.
List of World Pro winners:
 Bonnardel Cup: 1935–1937
This was a team tournament created by Bill Tilden and modeled on the Davis Cup format. In 1935, early rounds in France were hoped to be played at Roland Garros, but the French Tennis Association would not allow the event to played at the stadium.
 International Pro Championship of Britain: 1935–1939
The International Pro Championship of Britain (also known as the Stockport Pro, as well as the Southport Dunlop Cup for sponsorship purposes) was a professional tennis tournament held at Victoria Park in Southport between 1935 and 1939. It was open to professional players only, amateurs were not allowed to compete. The tournament was held on outdoor En-tout-cas, "all-weather" artificial clay.
List of International Pro Championship of Britain winners:
- 1935: Ellsworth Vines
- 1936: Hans Nüsslein
- 1937: Hans Nüsslein
- 1938: Hans Nüsslein
- 1939: Hans Nüsslein
 U.S Pro Hard Courts: 1945–1946
In LA; the only significant pro tournament of the last year of World War II.
 Philadelphia Indoor Pro: 1950–1952
 Australian Pro: 1954–1966
This had multiple venues from the east and west coasts of Australia and was not played in 1955, 1956, 1961 and 1963.
List of Australian Pro winners:
- 1954: Frank Sedgman
- 1957: Pancho Segura
- 1958: Frank Sedgman
- 1959: Lew Hoad
- 1960: Ken Rosewall
- 1962: Ken Rosewall
- 1964: Rod Laver
- 1965 (Adelaide): Rod Laver
- 1965 (Perth): Rod Laver
- 1966 (Adelaide): Ken Rosewall
- 1966 (Perth): Rod Laver
 Tournament of Champions: 1956–1959
The Tournament of Champions was a professional tennis tournament between 1956 and 1959. The tournament was held on the indoor hardcourts at Los Angeles in 1956, and on the grass-courts of Forest Hills, New York, between 1957 and 1959. The 1956, 1957, and 1958 tournaments all had a round robin format. In 1968, the tournament was picked up again for a one off tournament during the open era and called Jack Kramers Tournament of Champions held at Wembley Arena.
List of Tournament of Champions winners:
 Masters Pro: 1957–1965
Round Robin in Los Angeles, held from 1957 to 1959, and again in 1964 and 1965.
Masters Pro winners:
 Kramer Cup: 1961–1963
A team format tournament.
 Madison Square Garden Pro:1966–1967
Madison Square Garden Pro winners:
 Wimbledon Pro: 1967
The Wimbledon World Professional Championship, also known as the Wimbledon Pro, was held in August 1967. The tournament was sponsored and broadcasted by the BBC to mark the invention of colour television. It was first time that professional tennis players played at Wimbledon.
Wimbledon Pro winner:
- 1967: Rod Laver
- Robertson, Max (1974). Encyclopedia of Tennis. pp. 60–71.
- Geist, Robert (1999). Ken Rosewall: Der Grosse Meister. Austria. p. 137.
- Lee, Raymond (September 2007). "Greatest Player of All Time: A Statistical Analysis". Tennis Week Magazine.
- Chevallier, Jean-Pierre (2007). le Tennis en France 1875-1955. Alan Sutton. ISBN 978-2849106266.
- "Forgotten Victories". Retrieved September 26, 2012.
- "British Pro Championships". Retrieved September 26, 2012.
- "History of the Pro Tennis Wars Chapter VII". Retrieved September 25, 2012.
- "History of the Pro Tennis Wars, Chapter IX:". Retrieved September 25, 2012.
- McCauley, Joe. History of Professional Tennis.
- "Professional Tennis Ban". Barrier Miner. 1935. Retrieved September 26, 2012.
- History of the Pro Tennis Wars
- Chapter I: Suzanne Lenglen and the First Pro Tour
- Chapter II, Part 1: The eminence of Karel Kozeluh and Vincent Richards 1927–1928
- Chapter II, Part 2: Deja vu 1929–1930
- Chapter III: Tilden's Year of Triumph in 1931
- Chapter IV: Tilden and Nusslein, 1932–1933
- Chapter V: The Early Ascendancy of Vines, 1934
- Chapter VI: Vines's Second Year: 1935
- Chapter VII: Awaiting Perry, 1936
- Chapter VIII: Perry and Vines, 1937
- Chapter IX: Readying for Budge, 1938
- Chapter X: Budge's Great Pro Year, 1939
- Chapter XI: America, 1940–1941
- Chapter XI: America, 1942
- Chapter XII: The High War Years, 1943–1945