Chicago recalled Assad from Triple-A Iowa on Wednesday, Bruce Levine of 670TheScore.com reports.
Assad was optioned to Triple-A earlier this month after registering a 5.09 ERA over 17.2 innings with the Cubs in one start and four relief appearances. He'll rejoin the big club as a replacement in the bullpen for Nick Burdi, who was placed on the 15-day injured list after undergoing an appendectomy earlier Wednesday.