Objective: To study the personalities of the heroin dependants. Methods: 60 heroin dependants (detoxification?group) who were followed up over 6 months and divided into two groups (relapse group, who relapsed within 6?months and non-relapse group, who did not relapse within 6 months) after detoxification were tested by NEO-PI-R; 34?normal cases were selected and compared with them, statistical analysis was done by SPSS11.0. Results: The average?scores in the detoxification group on agreeableness and conscientiousness were lower than in the normal control group (P< 0.05); the average scores in detoxification group about angry hostility and vulnerability were higher than in the control?group(P<0.05); the average scores in detoxification group about values, trust, dutifulness, self-discipline, deliberation were?lower than in the control group(P<0.05). There was obvious difference only in warmth and trust between the relapse group?and non-relapse group. Conclusion: There are many severe personalities abnormality tendencies in the heroin dependants,?and further study about the personalities of easy relapse and personal integrity is needed.