The team said Desmond has a left oblique strain and has been bothered by the problem since before the All-Star break. The roster move is retroactive to Saturday, making Desmond eligible to come off the disabled list Aug. 12.
Desmond is hitting .289 with 17 home runs and 53 runs batted in in 89 games. He leads the Nationals in home runs and is second in RBI.
Washington recalled outfielder Corey Brown from Triple-A Syracuse to take Desmond's spot on the roster. It will be his third stint with the parent team. He played three games last season and three earlier this year. He has an RBI but is yet to collect his first major-league hit.