Objective: The purpose of this research was to explore the effectiveness of cognitive–behavioral therapy on mathematics problem–solving performance in fifth grade elementary school female students with mathematics disorder in Yazd. Method: 355 grade elementary female students with mathematics disorder were recruited, and evaluated utilizing Key-math test and assigned to two groups as experimental and control groups. The problem-solving test was administered as the pretest, posttest and follow up. The experimental group received ten cognitive–behavioral therapy sessions, and the control group did not receive any intervention. Results: The results of analysis of covariance showed that there was a significant difference among mean scores of math problem–solving performance in the two groups. Also the results of analysis of correlation displayed a significant correlation among problem-solving performance and IQ scores, average, math exam scores and Key-math score; solving performance and socio-economic status of subjects. Conclusion: Accordingly, we can suggest that cognitive–behavioral therapy can be applied as an effective therapeutic intervention for students with mathematics disorders.