Objective: To examine potential differential responses in men and women to cognitive behavior therapy for posttraumatic stress disorder (PTSD). Method: Fifty-two men and 56 women diagnosed with PTSD participated in randomized controlled trials of cognitive behavior therapy for PTSD. Participants were randomly allocated to either (a) exposure-only therapy (Ex) or (b) exposure-based treatment combined with cognitive restructuring (ExCR). Results: There were no significant differences between men and women in treatment response immediately after treatment in either Ex or ExCR. At 6-month follow-up, men displayed significantly more severe PTSD symptoms in the Ex group compared with women in the Ex group, and compared with men and women in the ExCR conditions. Conclusions: These findings suggest that men with PTSD have a reduced maintenance of treatment gains following exposure therapy compared with women, but display less relapse if exposure therapy is combined with cognitive therapy. These findings are consistent with evidence that women recall emotional memories and retain extinction memories more strongly than men, which may facilitate emotional processing and long-term treatment gains. (Contains 2 tables and 2 figures.)