List of champions of the 1904 U.S. National Championships tennis tournament (now known as the US Open). The men's tournament was held from August 21 to August 31 on the outdoor grass courts at the Newport Casino in Newport, Rhode Island. The women's tournament was held from June 21 to June 25 on the outdoor grass courts at the Philadelphia Cricket Club in Philadelphia, Pennsylvania. It was the 24th U.S. National Championships and the second Grand Slam tournament of the year.

Finals

Men's singles

🇺🇸 Holcombe Ward (USA) defeated 🇺🇸 William Clothier (USA) 10–8, 6–4, 9–7

Women's singles

🇺🇸 May Sutton (USA) defeated 🇺🇸 Elisabeth Moore (USA) 6–1, 6–2

Men's doubles

🇺🇸 Holcombe Ward (USA) / 🇺🇸 Beals Wright (USA) defeated 🇺🇸 Kreigh Collins (USA) / 🇺🇸 Raymond Little (USA) 1–6, 6–2, 3–6, 6–4, 6–1

Women's doubles

🇺🇸 May Sutton (USA) / 🇺🇸 Miriam Hall (USA) defeated 🇺🇸 Elisabeth Moore (USA) / 🇺🇸 Carrie Neely (USA) 3–6, 6–3, 6–3

Mixed doubles

🇺🇸 Elisabeth Moore (USA) / 🇺🇸 Wylie Grant (USA) defeated 🇺🇸 May Sutton (USA) / 🇺🇸 Trevanion Dallas (USA) 6–2, 6–1