Chen threw 42 pitches, 27 for strikes. He threw all of his pitches, as he did in his second bullpen session on Monday.
"He looks good," said Scott McGregor, the Orioles' pitching rehab coordinator. "It was a good test for him today. He threw all of them and looked pretty comfortable."
Chen will throw another bullpen session on Saturday and likely will pitch a four-inning simulated game on Monday before going out on an injury-rehab assignment. He's expected at Camden Yards next week.
"The big thing is for him to pitch Monday and we'll decide from there," McGregor said.
Orioles manager Buck Showalter recently said that Chen could be activated in time to make a few starts before the All-Star break.
Chen had thrown off a half-mound once and a regular mound twice before today's sim game. He hasn't pitched for the Orioles since straining his oblique during a May 12 start in Minnesota.