The 1964 U.S. National Championships (now known as the US Open) was a tennis tournament that took place on the outdoor grass courts at the West Side Tennis Club, Forest Hills in New York City, United States. The tournament ran from 2 September until 13 September. It was the 84th staging of the U.S. National Championships, and the fourth Grand Slam tennis event of 1964.

Roy Emerson defeated Fred Stolle 6–4, 6–1, 6–4

Maria Bueno defeated Carole Caldwell Graebner 6–1, 6–0

Chuck McKinley / Dennis Ralston defeated Graham Stilwell / Mike Sangster 6–3, 6–2, 6–4

Billie Jean Moffitt / Karen Susman defeated Margaret Smith / Lesley Turner 3–6, 6–2, 6–4^[2]

Margaret Smith / John Newcombe defeated Judy Tegart / Ed Rubinoff 10–8, 4–6, 6–3

• Official US Open website