Background:This study examined the comorbidity of personality disorders (PDs) and opiate dependence, and the extent of active
co-occurence of different PDs among opiate addicts in residential treatment. Method: Subjects were 80 consecutive consenting patients admitted into a residential opiate detoxification programme. PDs were measured by the Screening Test for Comorbid Personality Disorders-STCPD(developed in the UK). Results: The prevalence rate of any PD was 86%, while the rates for histrionic, dependent, avoidant and borderline PDs were 44%, 36%,35% and 76% respectively. There was an average number of five comorbid PDs in patients with more than one PD. Significant active co-occurrence of the following pairs of PDs was observed: dependent-avoidant (OR=13.9; 95% CI=4.55, 42.83), histrionic-dependent (OR=2.8; 95% CI=1.11, 7.26), borderline-histrionic (OR=5.5; 95% CI=1.45, 20.87),and borderline-dependent (OR=3.9; 95% CI=1.04, 15.04). Conclusion: The findings reveal substantial degree of comorbidity of PDs among opiate addicts and indicate the need to carry out full diagnostic interviews in patients with a positive screen for personality disorders. Given the high prevalence of positive screen for PDs, such diagnoses will enhance the development of treatment protocols that are responsive to the various features of PDs that could jeopardise favourable treatment outcomes.