The 2013 Citi Open (known as such for sponsorship reasons) was a tennis tournament played on outdoor hard courts.

It was the 45th edition (for the men) and the 3rd edition (for the women) of the event known that year as the Citi Open (previously known on the men's tour as the Legg Mason Tennis Classic), and was part of the ATP World Tour 500 series of the 2013 ATP World Tour, and of the WTA International tournaments of the 2013 WTA Tour.

FitzGerald Tennis Center in Washington, D.C., United States, from July 27 to August 4, 2013.

Juan Martín del Potro and Magdaléna Rybáriková won the singles titles.

The following players received wild cards into the main singles draw: The following players received entry from the singles qualifying draw: The following players received entry as lucky losers: The following pairs received wildcards into the doubles main draw: The following players received wild cards into the main singles draw: The following players received entry from the singles qualifying draw: Juan Martín del Potro defeated John Isner, 3–6, 6–1, 6–2 Magdaléna Rybáriková defeated Andrea Petkovic, 6–4, 7–6(7–2) Julien Benneteau / Nenad Zimonjić defeated Mardy Fish / Radek Štěpánek, 7–6(7–5), 7–5 Shuko Aoyama / Vera Dushevina defeated Eugenie Bouchard / Taylor Townsend, 6–3, 6–3