Wang, who's been on the DL since July 1 with a strained right hip, is 2-3 with a 7.61 ERA in seven games with the Nationals. He was 4-6 with a 5.51 ERA in 15 minor league rehab outings this season.
Washington also recalled outfielder Corey Brown from Triple-A Syracuse on Tuesday.
In other Nationals news, manager Davey Johnson said left-hander John Lannan will get his first start with the rotation during Washington's Sept. 14-16 series against Atlanta, according to the Washington Post. The Nationals recalled Lannan from Triple-A Syracuse on Friday.
The Nationals announced Sunday that ace Stephen Strasburg, who had Tommy John surgery to replace an elbow ligament two years ago, will start only twice more this season. Strasburg is projected to make his final two starts on Friday against Miami and on Sept. 12 in New York.
Information from The Associated Press was used in this report.