The results of the study showed that cannabis use is widespread among the prison population and there are indications that the use of other drugs is not confined only to inmates with a history of extensive drug use within the community. However, the comparisons also showed a significant decrease in the range of drugs used, frequency of use, and actual amounts used in prison. Most drug injectors had stopped injecting drugs during their current sentence. However, the study also showed that being prescribed methadone in the community, then having that treatment stopped upon entry to prison, was associated with subsequent sharing of injecting equipment in prison. The authors recommend that inmates be offered admission to a detoxification program with reduction- based oral prescribing upon admission. The continuation of high-risk behaviors among some inmates is of particular concern, especially in relation to HIV. 3 figures