: Background: The objective of this study was to investigate the effect of cognitive-behavioral therapy (CBT) on the psychological symptoms among patients with cancer. Materials and Method: The design of the study is quasi-experimental with pretest, post-test with a control group. 30 patients were randomly allocated into two groups: experimental group (15 patients) and control group (15 patients). The independent variable was cognitive-behavioral therapy which was administrated in 9 sessions on the experimental group while there was no psychological treatment for the control group. The research instrument was SCL-90-R. The data was analyzed using covariance analysis. Results: Cognitive-behavioral therapy led to reduction in psychological symptoms in all dimensions of SCL-90-R variables among patients of experimental group. Conclusion: It may also be used as a supplement method enhancing standard oncological treatment and improving the physician-patient relationship. [ZJRMS, 2012 14(2): 112-116]