O'Rourke pitched one inning in two appearances at Triple-A Rochester this season, allowing one run on three hits. He appeared in Rochester's game on Friday but threw one pitch.
He made 28 appearances with the Twins last year, posting a 6.14 ERA. He struck out 24 and walked 15 in 22 innings. He held lefties to a .171/.292/.268 slash line, but righties hit .231/.354/.410 against him.
"We saw enough of him last year to know what he's capable of doing," Twins manager Paul Molitor said. "The one knock on him, based on his track record in the past, is difficulty against right-handed hitters. His left-handed numbers have always been outstanding. I think he's improved in that regard."
O'Rourke was one of the final cuts in Spring Training after posting a 1.35 ERA with five strikeouts in 6 2/3 innings. But the Twins opted to call up fellow lefty Taylor Rogers over him when closer Glen Perkins was placed on the 15-day disabled list with a strained shoulder on Wednesday. Molitor said he made sure to talk about that decision with O'Rourke before the game to assure him that the organization still thinks highly of him.
"It kind of came down to a numbers pinch in spring," Molitor said. "I talked to him today about coming up here and helping us for a few days. I'm sure the Rogers move was on his mind a little bit. We talked about that a little bit. I think it's important to let guys know. Guys you have respect for. Kind of how some of those things work."
Rhett Bollinger is a reporter for MLB.com. Read his blog, Bollinger Beat, follow him on Twitter @RhettBollinger and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.