The present study aims to determine the efficacy of Cognitive Behavioral Therapy based on Hofmann’s model for decreasing symptoms of social anxiety disorder. 12 subjects with social anxiety disorder were selected using Social Phobia Inventory (SPIN) and Structured Clinical Interview for Diagnostic and Statistical Manual of mental disorders (SCID-IV). 6 subjects were randomly selected to be included in the test group and 6 subjects were included in the control group. The test group received CBT based on Hofmann’s model and the control group waited. Examinations showed that the 2 groups matched demographically. Subjects completed the Social Phobia Inventory (SPIN), the Liebowitz Social Anxiety Scale (LSAS-SR), and The Brief Fear of Negative Evaluation Scale (BFNE) questionnaires before, immediately after and 1.5 months after the end of treatment/ waiting. The results of analyses indicated that the independent variable (CBT based on Hofmann’s model) had a significant effect on the dependent variable (SPIN, LSAS-SR, BFNE) in repeated measurements (pre-test, post-test and follow up). Generally, the results were indicative of the efficacy of Cognitive Behavioral Therapy based on Hofmann’s model (2007) for decreasing different components of social anxiety disorder; as the efficacy was maintained from post-test to follow-up stage.