The intravenous drug use behaviour and HIV risk reduction strategies used by a group of Scottish inmates prior to prison, during imprisonment and as expected after release was investigated. From a sample of 559 inmates (480 males and 79 females) 27.5% were involved in IVDU prior to imprisonment, 7.7% on at least one occasion during a period of imprisonment and 14.7% expected to do so after release. Prior to imprisonment 17.3% had shared needles, 5.7% at some time during imprisonment and 4.3% expected to do so after release. Some form of HIV risk reduction strategies were practised by the majority of IVDU inmates prior to imprisonment, during imprisonment and were expected to continue after release. The most at risk inmates were those who continued to share injecting equipment without reduction and without sterilizing. The reduction in IVDU and needle sharing during imprisonment in comparison to prior to imprisonment was paralleled by a self-perceived reduction of personal risk from HIV during imprisonment.