| Date: | July 20–26 |
| Edition: | 29th |
| Category: | International Series Gold |
| Draw: | 56S / 28D |
| Prize Money: | $575,000 |
| Surface: | Hard / outdoor |
| Location: | Washington, D.C., United States |
| Champs: |  Andre Agassi[1] |
| Champd: | Grant Stafford / Kevin Ullyett[2] |
| Main Name: | Washington Open (tennis) Washington Open |
The 1998 Legg Mason Tennis Classic was a men's tennis tournament played on outdoor hard courts in Washington, D.C., United States, that was part of the International Series Gold of the 1998 ATP Tour. It was the twenty-ninth edition of the tournament and was held from July 20 through July, 26. Second-seeded Andre Agassi won the singles title.
See main article: article and 1998 Legg Mason Tennis Classic – Singles. Andre Agassi defeated 
Scott Draper, 6–2, 6–0
See main article: article and 1998 Legg Mason Tennis Classic – Doubles. Grant Stafford / 
Kevin Ullyett defeated 
Wayne Ferreira / Patrick Galbraith, 6–2, 6–4