The 1965 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 1 September until 12 September. It was the 85th staging of the U.S. National Championships, and the fourth Grand Slam tennis event of 1965.
See main article: 1965 U.S. National Championships – Men's singles. 
Manuel Santana defeated 
Cliff Drysdale 6–2, 7–9, 7–5, 6–1
See main article: 1965 U.S. National Championships – Women's singles. 
Margaret Smith defeated 
Billie Jean Moffitt 8–6, 7–5
Roy Emerson / Fred Stolle defeated Frank Froehling / Charles Pasarell 6–4, 10–12, 7–5, 6–3
Carole Graebner / Nancy Richey defeated Billie Jean Moffitt / Karen Susman 6–4, 6–4
Margaret Smith / Fred Stolle defeated Judy Tegart / Frank Froehling 6–2, 6–2