The purpose of this study was to examine the efficacy of cognitive-beh-aviour therapy of maternal obsessive-compulsive symptom on their children depression.Therefore, one of the fifth educationalregions of Isfahan and two elementary school of this region were randomly selected.Then 260student’ s mothers in grade one and two were asked to complete Moudzly Obsessive-Compulsive Inventory (MOCI) and Ontario Child HealthScale (OCHS). The result of Pearson correlation showed a correlation of 0.49 between mother’ s obsession and her child depression. This correlation was significant at the level of 0.01 (2- tailed). In the second step 40 mothers with highest MOCI score wereinterviewed. As a result 32 mothers received the diagnosis of OCD. These subjects were randomly divided into two experimental and control groups. The 8 cognitive-behaviour therapy sessions of 90 minutes addressing parenting styles, " perfectionism" a cause of anxiety, relaxation, logical errors, challenging thoughts, exposure and response prevention (E/RP) were conducted during one month on the experimental group. The control group received no intervention. The MOCI and OCHS scores were taken at pre-test and post-test. One month later they were followed-up using the same scales. The results of analysis of covariance showed that symptoms of maternal OCD in the experimental group was significantly reduced in comparison to the control group in post-test and follow-up phases (p< 0.0001). The mean score of childdepressiondidn' t decrease significantly in comparison to the control group at post-test (P=0.118), but it was decreased in the follow-up phase (P=0.012).