As part of the Australian Treatment Outcome Study (ATOS), 177 (88%) heroin users entering detoxification (DTX) and 66 (83%) heroin users not in treatment (NT) were interviewed at baseline and 3 months to examine drug use, risk-taking, overdose, crime and psychopathology outcomes. The majority (76%) of the DTX group had entered additional treatment at 3 months, mainly further detoxification, and 54% were currently in treatment, mainly maintenance and residential rehabilitation. There were reductions in heroin use and other drug use in those entering detoxification. Forty-two per cent were abstinent at 3 months compared to 20% in the NT group. There were also reductions in crime among those entering DTX, and less marked reductions in the NT group. Psychopathology showed less change. Detoxification may, in some part, function as a gateway to further treatment and those entering DTX showed modest but significant improvements across drug use and crime at 3 months.