Strasburg, the hard-throwing No. 1 pick in last year's draft, will have the reconstructive elbow operation known as Tommy John surgery on Friday. He finished his rookie season with a 5-3 record and 2.91 ERA.
Washington also elevated shortstop Danny Espinosa to the 40-man roster from Triple-A Syracuse and recalled catcher Wilson Ramos from Syracuse.
Espinosa had 22 home runs and 25 stolen bases in the minors this season.
"He plays second and short, so he'll do both up here," National manager Jim Riggleman said, "but he'll get significant time at second base."