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.
He was the father of Clare MacIntyre, the woman who was the inspiration for Harry Chapin's 1972 song Taxi.