The aim of this study was to determine the effectiveness of metacognitive therapy on reducing rumination and anxiety in obsessive-compulsive patients. The method of the present study was a quasi-experimental experimental method in terms of data collection and its research design was a pre-test post-test design with a control group. The study population consisted of all patients referred to counseling and psychological clinics in District 5 of Tehran. Sampling method The present study was purposive stepwise cluster sampling. Based on previous research, 15 people were selected for each group, which was a total of 30 people. Metacognitive therapy training package and two questionnaires were used to evaluate the dependent variables of the research. In this study, subjects were trained in metacognitive skills for 8 weeks and 16 sessions of 90 minutes. It was used according to the latest DSM 5 criteria. The results of analysis of covariance showed that metacognitive therapy reduced rumination and anxiety in obsessive-compulsive patients. When obsessive-compulsive patients become aware of their skills, talents, feelings, beliefs, attitudes, and cognitive and social abilities, and thus overcome their mental rumination and anxiety, they are therefore performing well and doing their homework. At the right time and with the right quality, they will experience successful treatment.