Washington manager Jim Riggleman says Strasburg was expected to throw at about 50 percent Monday in Viera, Fla. Strasburg had been throwing off flat ground.
The overall No. 1 pick from the 2009 draft seemed excited about his return. He posted on Twitter: "First bullpen in the books. Felt great! Hopefully time will speed up now!"
The 22-year-old pitching phenom had ligament replacement surgery on his right elbow Sept. 3. It is expected to take 12 to 18 months for him to return to the majors.
Strasburg struck out 14 in his big league debut last June and went 5-3 with a 2.91 ERA in 12 starts.