A substantial proportion of people with hepatitis C cycle through the criminal justice system, making prisons one of the most important settings for hepatitis C virus (HCV) prevention, testing, and treatment. Scaling up treatment could therefore play a major role in driving down HCV prevalence and curbing hepatitis C epidemics worldwide, according to studies presented at the 5th International Symposium on Hepatitis Care in Substance Users (INHSU 2016) this week in Oslo.