List of champions of the 1905 U.S. National Championships tennis tournament (now known as the US Open). The men's tournament was held from August 22 to August 31 on the outdoor grass courts at the Newport Casino in Newport, Rhode Island. The women's tournament was held from June 20 to June 24 on the outdoor grass courts at the Philadelphia Cricket Club in Philadelphia, Pennsylvania. It was the 25th U.S. National Championships and the second Grand Slam tournament of the year.
See main article: 1905 U.S. National Championships – Men's singles. 
Beals Wright (USA) defeated Holcombe Ward (USA) 6–2, 6–1, 11–9
See main article: 1905 U.S. National Championships – Women's singles. Elisabeth Moore (USA) defeated Helen Homans (USA) 6–4, 5–7, 6–1
Holcombe Ward (USA) / Beals Wright (USA) defeated Fred Alexander (USA) / Harold Hackett (USA) 6–4, 6–4, 6–4
Helen Homans (USA) / Carrie Neely (USA) defeated Marjorie Oberteuffer (USA) / Virginia Maule (USA) 6–0, 6–1
Augusta Schultz (USA) / Clarence Hobart (USA) defeated Elisabeth Moore (USA) / Edward Dewhurst (USA) 6–2, 6–4