1903 U.S. National Championships – Men's singles

Men's singles
1903 U.S. National Championships
Champion Laurence Doherty
Runner-up William Larned
Score6–0, 6–3, 10–8

Laurence Doherty defeated the two-time defending champion William Larned 6–0, 6–3, 10–8 to win the men's singles tennis title at the 1903 U.S. National Championships. Doherty had defeated William Clothier in the All Comers' Final, which was delayed by a day due to rain.

The event was held at the Newport Casino in Newport, R.I., United States. The entry list consisted of 97 players, which was slightly smaller than that of the previous year.