Drug users are vastly overrepresented in prison populations. Once inside they face increased risks of acquiring infections such as HIV, hepatitis and TB, and on release they face an elevated risk of fatal overdose. Relapse and recidivism are the norm following release from prison. The implementation of evidence-based drug treatment programmes in prison is rare, yet drug treatment in prison reduces the transmission of infections, recidivism and fatal overdose on release. Recognising the negative returns associated with incarceration, many jurisdictions have begun to consider alternatives such as depenalisation of the personal use of illicit drugs, provision of treatment and social reintegration of drug offenders, and a shift in focus from supply reduction to demand and harm reduction measures in the community and in prison. Women with drug problems are twice as likely to have been imprisoned for a drug offence as incarcerated men. Similarly, HIV prevalence is higher among female inmates. Serious attention should be paid to implementation of non-custodial sentences for women, particularly during pregnancy and those with young children.