Sexual self-esteem is negatively influenced by the stressful experiences in lifetime. This study compared the sexual self-esteem and its components in mothers with normal and mentally-retarded children in Qaen city, in 2014. A total of 120 mothers were selected and assigned into two groups of 60 samples based on convenient sampling method and randomized multiple stage sampling. Both groups completed sexual self-esteem questionnaire. The data were analyzed employing t-test through SPSS software version15. The results showed that the rate of sexual self-esteem in mothers of mentally-retarded children decreased significantly compared with that of mothers with normal children (p<0.05). Moreover, the mean scores of all components of sexual self-esteem including skill and experience, attractiveness, control, moral judgment, and adaptiveness in mothers of mentally-retarded children were significantly less than those of mothers with normal children (p <0.05). Therefore, it is recommended that self-esteem, especially the sexual one, be taught to mothers of mentally-retarded children by specialists.