| 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] | |
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.