The 1955 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 11 September.

It was the 75th staging of the U.S. National Championships, and the fourth Grand Slam tennis event of the year.

Tony Trabert (USA) defeated Ken Rosewall (AUS) 9–7, 6–3, 6–3 Doris Hart (USA) defeated Patricia Ward (GBR) 6–4, 6–2 Kosei Kamo (JPN) / Atsushi Miyagi (JPN) defeated Gerald Moss (USA) / Bill Quillian (USA) 6–2, 6–3, 3–6, 1–6, 6–4 [2] Louise Brough (USA) / Margaret Osborne duPont (USA) defeated Shirley Fry (USA) / Doris Hart (USA) 6–3, 1–6, 6–3 [3] Doris Hart (USA) / Vic Seixas (USA) defeated Shirley Fry (USA) / Gardnar Mulloy (USA) 7–5, 5–7, 6–2 [4]