The Legg Mason Tennis Classic was the third ATP stop of the 2009 US Open Series.

Unlike previous years, the men's event was field 48 players instead of 32.

Second-seeded Juan Martín del Potro won the singles title.

Martin Damm / Robert Lindstedt defeated Mariusz Fyrstenberg / Marcin Matkowski, 7–5, 7–6(7–3).

List of Association of Tennis Professionals (ATP) singles entrants, as of July 27, 2009.