The aim of this study is to compare the strategies of cognitive emotion regulation and mindfulness in people who have or have not committed infidelity which was done using a descriptive comparative research method. From all divorce applicants in Mashhad courts, 100 people (50 people who have engaged and 50 people who have not engaged in extramarital relationships) were selected by available sampling method. Data were collected by cognitive emotional regulation strategies and mindfulness skills questionnaires and analyzed by multivariate analysis of variance. The results showed that there are differences between emotion regulation strategies and mindfulness skills between the two groups, so that in positive cognitive regulation, positive refocusing, positive evaluation, planning, broader perspective, acceptance, action with awareness, description, observation, non-judgment and non-reaction, the scores of people who had not committed extramarital relations were higher than those with experience of extramarital relationship. On the other hand, the group who had engaged in extramarital relationships had scored lower on negative cognitive regulation, self blame, blaming others, rumination, and catastrophizing. This study showed that mindfulness and emotion regulation skills can act as a deterrent to extramarital relationships and training these skills can be useful for couples.