| 1908 U.S. National Championships | |
|---|---|
| Date | August 18–29 (M) June 22–27 (W)  | 
| Edition | 28th | 
| Category | Grand Slam | 
| Surface | Grass | 
| Location | Newport, R.I., United States (M)  Philadelphia, PA, United States (W)  | 
| Champions | |
| Men's singles | |
| Women's singles | |
| Men's doubles | |
| Women's doubles | |
| Mixed doubles | |
List of champions of the 1908 U.S. National Championships tennis tournament (now known as the US Open). The men's tournament was held from August 18 to August 29 on the outdoor grass courts at the Newport Casino in Newport, Rhode Island. The women's tournament was held from June 22 to June 27 on the outdoor grass courts at the Philadelphia Cricket Club in Philadelphia, Pennsylvania. It was the 28th U.S. National Championships and the second Grand Slam tournament of the three played that year.
Finals
Men's singles
 William Larned (USA) defeated 
 Beals Wright (USA) 6–1, 6–2, 8–6
Women's singles
 Maud Barger-Wallach (USA) defeated 
 Evelyn Sears (USA) 6–3, 1–6, 6–3
Men's doubles
 Fred Alexander (USA) / 
 Harold Hackett (USA) defeated 
 Raymond Little (USA) / 
 Beals Wright (USA) 6–1, 7–5, 6–2
Women's doubles
 Evelyn Sears (USA) / 
 Margaret Curtis (USA) defeated 
 Carrie Neely (USA) / 
 Miriam Steever (USA) 6–3, 5–7, 9–7
Mixed doubles
 Edith Rotch (USA) / 
 Nathaniel Niles (USA) defeated 
 Louise Hammond Raymond (USA) / 
 Raymond Little (USA) 6–4, 4–6, 6–4