Major social problems are always reflected within the prison community and programmes for the rehabilitation of offenders should include provision to tackle them. Drug addiction, particularly to narcotics, is one such problem, and intervention for treatment is appropriate at the time the offender is placed in the custody of the Prison Service. Based on the Hong Kong experience, the period required for treatment and the procedures by which treatment takes place is discussed; so too is the treatment programme and the necessity for after‐care. Statistics illustrating the success of the programme are included.