1903 U.S. National Championships
Date	August 18–26 (M) June 24–27 (W)
Edition	23rd
Category	Grand Slam
Surface	Grass
Location	Newport, R.I., United States (M) Philadelphia, PA, United States (W)
Champions
Men's singles
Laurence Doherty[1]
Women's singles
Elisabeth Moore[1]
Men's doubles
Reginald Doherty / Laurence Doherty
Women's doubles
Elisabeth Moore / Carrie Neely[1]
Mixed doubles
Helen Chapman / Harry Allen[1]
← 1902 · U.S. National Championships · 1904 →

List of champions of the 1903 U.S. National Championships tennis tournament (now known as the US Open). The men's tournament was held from August 16 to August 24 on the outdoor grass courts at the Newport Casino in Newport, Rhode Island. The women's tournament was held from June 24 to June 27 on the outdoor grass courts at the Philadelphia Cricket Club in Philadelphia, Pennsylvania. It was the 23rd U.S. National Championships and the second Grand Slam tournament of the year. British Laurence Doherty became the first non-US winner of the men's championship.

Finals

Men's singles

Laurence Doherty (GBR) defeated William Larned (USA) 6–0, 6–3, 10–8 ^[2]

Women's singles

Elisabeth Moore (USA) defeated Marion Jones (USA) 7–5, 8–6 ^[3]

Men's doubles

Reginald Doherty (GBR) / Laurence Doherty (GBR) defeated Kreigh Collins (USA) / Harry Wainder (USA) 7–5, 6–3, 6–3

Women's doubles

Elisabeth Moore (USA) / Carrie Neely (USA) defeated Miriam Hall (USA) / Marion Jones (USA) 4–6, 6–1, 6–1

Mixed doubles

Helen Chapman (USA) / Harry Allen (USA) defeated Carrie Neely (USA) / W. H. Rowland (USA) 6–4, 7–5