The 1939 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, United States. The tournament ran from 7 September until 17 September. It was the 59th staging of the U.S. National Championships and the fourth Grand Slam tennis event of the year.

Bobby Riggs defeated Welby van Horn 6–4, 6–2, 6–4

Alice Marble defeated Helen Jacobs 6–0, 8–10, 6–4