1999 US Open – Mixed doubles
| Mixed doubles | |
|---|---|
| 1999 US Open | |
| Champions | Ai Sugiyama Mahesh Bhupathi |
| Runners-up | Kimberly Po Donald Johnson |
| Score | 6–4, 6–4 |
The 1999 US Open mixed doubles was the mixed doubles event of the hundred-and-ninth edition of the US Open, the fourth and last Grand Slam of the year. Serena Williams and Max Mirnyi were the defending champions but did not compete that year.
Ai Sugiyama and Mahesh Bhupathi won in the final against unseeded Americans Kimberly Po and Donald Johnson, 6–4, 6–4.