BACKGROUND: The prevalence of personality disorders (PD) in the South African population is largely unknown. Thus, we undertook to estimate prevalence, demographic correlates, co-morbidity and treatment rates of DSM-IV PD among South Africans. SAMPLING AND METHODS: A three-stage probability sample design was used. Of the 4,433 interviews obtained, based on quality control criteria, 4,315 interviews were retained for analysis. All participants were screened for PD and axis I disorders with the World Health Organisation Composite International Diagnostic Interview. The multiple imputation method was then used to estimate prevalence. RESULTS: The multiple imputation prevalence estimate in the total sample was 6.8%. All three PD clusters were significantly co-morbid with each other and with other axis I disorders. Male gender was the only significant predictor of PD. Of note was the finding that less than one fifth of participants with a possible PD diagnosis had received treatment for a mental health or substance abuse problem in the previous 12 months. CONCLUSION: The high co-morbidity of PD with axis I disorders in South Africa is consistent with previous reports elsewhere. However, more research is indicated to determine the reasons for the higher prevalence of cluster A disorders than of cluster B and C disorders in this population. (c) 2008 S. Karger AG, Basel.