Wagner, who hasn't played in a Major League game since May 2007 because of a SLAP (superior labrum anterior to posterior) tear in his right shoulder, threw 20 pitches -- his changeup, slider and fastball -- for strikes.
Wagner will pitch in a simulated game on Saturday and then make a rehab start next week for Class A Potomac. There is no timetable set for Wagner's return to the Major Leagues.
"It went very well," Wagner said. "I thought the ball was coming out very well. I was able to throw all my pitches."
Nationals pitching coach Randy St. Claire said that Wagner's outing was better than his bullpen sessions.
"He looked free and easy," St. Claire said. "His warmups were better than the other day, his bullpen [session] was better, and his 20 pitches out on the mound were better than the bullpen [sessions]."
Also on Thursday morning, outfielder Austin Kearns spoke to the media for the first time since having surgery to remove loose bodies from his right elbow. He believes he will be back in action soon, but the Nationals have not announced a timetable.
Kearns said he can feel a big difference in the elbow since the surgery. He also said that he was not hurting before feeling pain in the elbow on May 18. Prior to the injury, Kearns was off to a slow start, hitting .187 with three home runs and 16 RBIs.
"On the field, I could do what I should do -- help out," Kearns said. "I don't think that was the cause for anything."
Second baseman Ronnie Belliard is expected to join Double-A Harrisburg on Friday for a rehab assignment. Belliard has been on the disabled list since May 16 with a strained left calf.
This is the second Major League rehab for the Senators this year. First baseman Dmitri Young was with Harrisburg for three days in May recovering from a back injury.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.