The 2018 Washington Open (called the Citi Open for sponsorship reasons) was a tennis tournament played on outdoor hard courts.

It was the 50th edition (for the men) and the 8th edition (for the women) of the Washington Open.

The event was part of the ATP World Tour 500 series of the 2018 ATP World Tour, and of the WTA International tournaments of the 2018 WTA Tour.

FitzGerald Tennis Center in Washington, D.C., United States, from July 30 to August 5, 2018.

[1] 1 Qualifiers prize money is also the Round of 64 prize money * per team The following players received wild cards into the main singles draw: The following player received entry using a protected ranking: The following players received entry from the singles qualifying draw: The following player received entry as a lucky loser: The following pairs received wildcards into the doubles main draw: The following pair received entry from the doubles qualifying draw: The following players received wild cards into the main singles draw: The following players received entry as a special exempt: The following players received entry from the qualifying draw: The following players received entry as lucky losers: The following pair received a wildcard into the doubles main draw: The following pair received entry as alternates: