BackgroundSocial anxiety is one of the most common psychological disorders that exists among children and adolescents, and it has profound effects on their psychological states and academic achievements.ObjectivesThe aim of this study was to determine the effectiveness of mindfulness-based cognitive therapy (MBCT) on diminishing social anxiety disorder symptoms and improving the self-esteem of female adolescents suffering from social anxiety.Patients and MethodsSemi-experimental research was conducted on 30 female students diagnosed with social anxiety. From the population of female students who were studying in Tehran’s high schools in the academic year of 2013 - 2014, 30 students fulfilling the DSM-5 criteria were selected using the convenience sampling method and were randomly assigned to control and experimental groups. The experimental group received eight sessions of MBCT treatment. The control group received no treatment. All participants completed the social phobia inventory (SPIN) and Rosenberg self-esteem scale (RSES) twice as pre- and post-treatment tests.ResultsThe results from the experimental group indicated a statistically reliable difference between the mean scores from SPIN (t (11) = 5.246, P = 0.000) and RSES (t (11) = -2.326, P = 0.040) pre-treatment and post-treatment. On the other hand, the results of the control group failed to reveal a statistically reliable difference between the mean scores from SPIN (t (12) = 1.089, P = 0.297) and RSES pre-treatment and post-treatment (t (12) = 1.089, P = 0.000).ConclusionsThe results indicate that MBCT is effective on both the improvement of self-esteem and the decrease of social anxiety. The results are in accordance with prior studies performed on adolescents.