The aim of the present study was toinvestigate the effectiveness of mindfulness-based cognitive therapyin reducing generalized anxiety in female elementary students. This clinical trial was conducted with the participation of 14 children with generalized anxiety disorder in Isfahan. They were randomly assigned to two mindfulness based cognitive therapy group (7 individuals) and control group (7 individuals). Participants’ worry and anxiety was assessed using PennsylvaniaState Worry Questionnaire-Child version and Revised Children’s Manifest Anxiety Scale at pre-test, post-test and two months after intervention.Covariance analysis was used to analyze data. The results indicate that mindfulness training significantly decreases the worry and anxiety in children with generalized anxiety disorder. The obtained results confirm the effectiveness of mindfulness-based cognitive therapy on generalized anxiety disorder in female elementary students.