Romero had been on the DL since July 23 with a lingering strained left forearm. His last appearance came July 19 at Florida when he pitched one-third of an inning and stranded two inherited runners.
For a tired bullpen which has used 17 pitchers this season, it was certainly something positive before a huge four-game series against the Astros.
Phillies manager Charlie Manuel didn't waste time sending in his veteran left-hander. Romero threw a scoreless eighth inning Monday, giving up two hits in an 8-2 loss.
"He did all right," Manuel said. "He threw some changeups and fastballs. He needs a little more time. He did OK."
Romero threw 21 pitches, 13 for strikes.
"I felt OK," Romero said. "It's never good when you lose a game. From a personal standpoint, I was pleased."
In other bullpen news, Brett Myers threw on the side Monday and Chan Ho Park was scheduled to throw a bullpen session in Clearwater, Fla.
As for the closer role, it looks to be open with the edge going to Ryan Madson. The hard-throwing right-hander is 5-5 with a 3.27 ERA with nine saves in 15 chances, including a four-out save in Sunday's 6-5 win at Milwaukee.
Brad Lidge, who has struggled all season, is 0-8 with a 7.51 ERA and 11 blown saves, the most in the Majors.
Tyler Walker was given a chance Saturday at Milwaukee, but he allowed a two-run walk-off homer to Ryan Braun in a 7-5 loss to the Brewers.
"You really prepare to get in there in about the fifth inning," said Walker, who had 34 saves in 48 opportunities with the Giants, including a career-best 23 in 2005. "From that point on, it's my job to prepare and to be ready when the phone rings."
However, Walker had a rough outing Monday, allowing two earned runs without retiring a batter in the seventh.
Andy Jasner is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.