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.

[2] Doherty had defeated William Clothier in the All Comers' Final, which was delayed by a day due to rain.

[3][4] The event was held at the Newport Casino in Newport, R.I., United States.

[1][5] The entry list consisted of 97 players, which was slightly smaller than that of the previous year.