This study aimed to investigate the effectiveness of Ellis’s rational-emotional approach on criminal thinking and law-evasion in male prisoners. A quasi-experimental design utilizing pretest, post-test, and follow-up test and waiting-list control groups was conducted. Thirty male prisoners were selected by purposeful sampling and randomized into experimental and waiting list control groups. Participants of experimental group received 12 sessions of Ellis’s rational-emotional approach intervention; and all participants answered to PICTS-L-SF and ABAWS as dependent variables at 3 time points (pretest, post-test, and 1 month follow-up). A repeated measures analysis of variance was used to analyze the data. Results showed criminal thinking and law-evasion in experimental group, as compared to control, at post-test phase was significantly decreased ( p < .05); and improvement of dependent variables in the follow-up phase has also been continued ( p < .05). Therefore, REBT can be beneficial for reducing criminal and illegal thoughts and behaviors among prisoners.