| Date: | August 9–17 |
| Edition: | 40th |
| Prize Money: | $483,000 |
| Draw: | 32S / 16D |
| Surface: | Hard / outdoor |
| Location: | Washington, D.C., US |
| Venue: | William H.G. FitzGerald Tennis Center |
| Champs: |  Juan Martín del Potro[1] |
| Champd: |  Marc Gicquel /  Robert Lindstedt[2] |
| Main Name: | Washington Open (tennis) Washington Open |
The 2008 Legg Mason Tennis Classic was a men's tennis tournament played on outdoor hard courts. It was the 40th edition of the Legg Mason Tennis Classic, and was part of the International Series of the 2008 ATP Tour. It took place at the William H.G. FitzGerald Tennis Center in Washington, D.C., United States, from August 9 through August 17, 2008.
The singles were led by ATP No. 9, San Jose and Dubai titlist, Los Angeles finalist, and defending champion Andy Roddick, winner of back-to-back titles in Stuttgart, Kitzbühel and Los Angeles Juan Martín del Potro, and Dubai finalist and Wimbledon quarterfinalist Feliciano López. Other seeds were Indian Wells quarterfinalist Tommy Haas, Indian Wells runner-up and Los Angeles semifinalist Mardy Fish, Marat Safin, Marc Gicquel and Marcel Granollers.
See main article: 2008 Legg Mason Tennis Classic – Singles. Juan Martín del Potro defeated 
Viktor Troicki, 6–3, 6–3
See main article: 2008 Legg Mason Tennis Classic – Doubles. Marc Gicquel / Robert Lindstedt defeated 
Bruno Soares / Kevin Ullyett, 7–6(8–6), 6–3