The present study aims at investigating the effectiveness of cognitive behavioural couple therapy on marital stress and emotional skills of infidel couples. Methods: A pre-test, post-test methodology with one control group is used. Forty couples were chosen purposefully from the statistical population of all infidel couples who referred to psychological clinics in Shiraz. The samples of 40 couples were put in to two groups consisting of a control group and experimental group. The measuring tools were Stockholm marital stress scale (SMSS) and Toronto alexithymia scale. The data and hypothesis were analyzed via SPSS-22, using multivariable analysis of covariance (MANCOVA). Result: The results of the study show that cognitive behavioural couple therapy has a meaningful effect on marital stress and emotional skills of infidel couples.