This study aimed to test whether there were any psychological differences between drug distributors, drug addicts and healthy individuals who were not associated with drug use. The research was conducted with use of a Myers-Briggs Typology Indicator (MBTI) questionnaire, personality questionnaire of G. Ayzenk (EPI), version A, questionnaire of manifestation of personality accentuation by Leongard - Shmishek, technique for detection of irrational beliefs by A. Ellis, questionnaire “The list of feelings”. We found statistically significant difference in degrees of manifestation of irrationality (MBTI) between the examined groups. The revealed correlation communications go well with Jung’s hypothesis concerning psychological features of rational and irrational types.