<p><strong>Background. </strong>There are no studies in South Africa (SA) on the outcomes following detoxification and psychosocial rehabilitation of heroin-dependent patients.</p><p><strong>Objective. </strong>To compare the demographic, clinical, forensic and treatment data of active heroin users v. users who were abstinent at the time of interview 4 years after attending the Opioid Detoxification Unit at Stikland Hospital in the Western Cape Province, SA. </p><p><strong>Method.</strong> Participants included patients above the age of 16 years who had been admitted to the Opioid Detoxification Unit at Stikland Hospital for heroin detoxification between July 2006 and June 2007. Participants were individually interviewed (either in person or telephonically) using a structured self-report questionnaire to collect demographic, clinical, forensic and treatment data 4 years following heroin detoxification treatment at this unit. </p><p><strong>Results.</strong> Of the participants, 60% were abstinent and a large portion (34%) attributed this to social support. Furthermore, there was a significant (<em>p</em>=0.04) difference in the longest period of abstinence between the past user group and active users, with more participants in the past user group being abstinent for 18 months or longer (<em>n</em>=24, 57%) than in the active users group (<em>n</em>=8, 29%). Active users (<em>n</em>=18, 64%) had significantly (<em>p</em>=0.03) more legal problems than abstinent users (<em>n</em>=14, 33%). Most participants (<em>n</em>=38, 54%) relapsed within 3 months after index detoxification and rehabilitation.<strong> </strong></p><p><strong>Conclusion.</strong> Active users had more legal problems than abstinent users, with social support structures playing a pivotal role in abstinence. Future research should assess the impact of interventions such as post-discharge social support programmes on criminality and heroin use in those that relapse following treatment.</p>