A minority of people who inject drugs (PWID) were tested for Hepatitis C Virus (HCV) in the past 12 months-7.0%–21.5% per city. Of those knowing to be infected with HCV, less than 25% received treatment. More than a half of PWID in both cities reported misuse of opioid agonist treatment (OAT). Incarceration was an independent correlate of anti-HCV positivity in Split. Improvements in OAT and needle and syringe exchange programs (NSEP) provision and access to NSEP in prisons are needed.