Abstract: Recent studies have suggested that Cognitive Behavior Therapy (CBT) is an effective treatment for anxiety disorders. Yet, many questions remain regarding the overall effectiveness of CBT. This controlled clinical trial was done to evaluate the efficacy of short term CBT treatment in Iranian outpatients with GAD. The study was performed in Baharan psychiatric center of Zahedan University of medical sciences (Zahedan-Iran). Twenty-one GAD patients were included in the study. From this group, 7 patients were randomly assigned to 8 sessions of CBT, seven patients were treated with antidepressant and Benzodiazepine drugs and the other 7 participants assigned to control group (Placebo). CBT was done in accordance with a manual. All patients completed at pre and post treatment the BAI, HARS and DAS. The results showed that both short term CBT and pharmacotherapy significantly produced symptoms reduction (BAI and HARS scores) in GAD patients comparing with placebo. Significant reduction of DAS scores only was observed in CBT group. Overall, short term CBT is an effective method of treatment for Iranian outpatients with GAD. Further research in this area will need to focus on comparing CBT with other psychological treatments.