ABSTRACT The study aimed to: (1) analyze differences between psychopathic and non-psychopathic offenders in terms of difficulties in emotion regulation and callous-unemotional traits, (2) investigate the association between difficulties in emotion regulation and callous-unemotional traits among psychopathic and non-psychopathic offenders, and (3) examine the mediation role of guilt in the relationship between difficulties in emotion regulation and callous-unemotional traits among non-psychopathic offenders, controlling for the level of desirable responses. The participants were 191 incarcerated male adult offenders serving their sentences in closed and semi-open custody. The incarcerated offenders participated in a semi-structured interview and completed self-report measures of emotion dysregulation, guilt, callous-unemotional traits, and social desirability. According to the results on the Hare Psychopathy Checklist-Revised, 60 (27.9%) participants were included in the psychopathic group, while 131 (60.9%) were non-psychopathic. The results showed a positive relationship between difficulties in emotion regulation, callousness, and psychopathy. The multiple regression analysis indicated that guilt contributed to the variance of callousness. Guilt was a mediator in the relationship between difficulties in emotion regulation and callousness among the group of non-psychopathic incarcerated offenders. The current study highlighted the importance of guilt as an adaptive moral emotion useful in the treatment of several psychological problems among male offenders.