Objectives: The present research investigates the efficacy of Group Cognitive-Remediation Therapy (GCRT) in decreasing clinical symptoms and enhancing cognitive performance among patients with schizophrenia. Method: Forty subjects were randomly selected from inpatients with at Razi Psychiatry Schizophrenia Hospital, and were assigned to one experimental and one control group, each one comprising 20 subjects. Both groups received drug therapy, and the experimental group received 16 sessions of GCRT in addition. Subjects were examined before, during and after intervention, using measures for assessing positive and negative symptoms, neuro-behavioral and cognitive examination, and nurse observation. Data were analyzed using multivariate repeated measures. Results: GCRT had decreased positive and negative symptoms in patients in the experimental group, and enhanced their cognitive performance. However, it had no effect on behavioral performance. Conclusion: Treatment of patients with schizophrenia requires a multifaceted program, which takes cognitive disorders into consideration. GCRT, which is based upon the Iranian socio-cultural situation, could be effective for improving cognitive disorders and decreasing clinical symptoms.