| 1918 U.S. National Championships | |
|---|---|
| Date | August 26 – September 3 (M) June 17 – 22 (W) |
| Edition | 38th |
| Category | Grand Slam (ITF) |
| Surface | Grass |
| Location | Forest Hills, Queens New York City, U.S. (M) Chestnut Hill, PA, U.S. (W) |
| Venue | West Side Tennis Club (M) Philadelphia Cricket Club (W) |
| Champions | |
| Men's singles | |
 Robert Lindley Murray[1] | |
| Women's singles | |
 Molla Bjurstedt[1] | |
| Men's doubles | |
 Bill Tilden / Vincent Richards[2] | |
| Women's doubles | |
| Marion Zinderstein / Eleonora Sears[3] | |
| Mixed doubles | |
| Hazel Wightman / Irving Wright[4] | |
The 1918 U.S. National Championships (now known as the US Open) was a tennis tournament that took place on the outdoor grass courts at the West Side Tennis Club, Forest Hills in New York City, United States. The women's tournament was held from June 17 until June 22 while the men's tournament ran from August 26 until September 3. It was the 38th staging of the U.S. National Championships and due to World War I the only Grand Slam tennis event of the year.