MacIntyre played four years of lacrosse while at Yale and was a first-team All-American his senior year. He continued to play at Oxford where he won three letters. In 1931, he toured the United States with an Oxford-Cambridge team which defeated both Army and Navy. While in England, he was selected three times to the All-Star English team. He coached Yale's lacrosse team when he returned for law school. In 1966, he was inducted into the National Lacrosse Hall of Fame.