Twenty-four drug injectors recruited from the community in England participated in small group discussions and interviews regarding drug injectors' experiences in prison. The following broad themes emerged as important: entering prison and early experiences; prison conditions; prison regimes; days in the lives of drug injectors; relationships and social networks; and informal rules and attitudes. These issues had been peripheral to studies about drug injectors' prison lives, which tended to focus on HIV-related risk behavior and neglected the wider social environment. Exploring the problems drug injectors face inside prison can help to sensitize both researchers and policymakers to some of the issues that are at the heart of of finding effective responses to the problems raised by drug use. The article concludes that understanding more about these issues can inform strategies that aim to reduce drug-related harm, strategies that must be underpinned by evidence. Table, references