Injection drug users constitute the largest group of person at high risk for acquiring chronic hepatitis C, B and Delta. In particular viral, host and environmental factors all seem to favour rapid spread of these infections among drugs addicts. Host factors include behaviours that expose individuals to hepatitis virus such as the shared use of drug preparation, injection equipment and not protected sexual relationship with other drugs users. While in some clinical studies adherence to treatment regimens was often poor and to treat chronic hepatitis in injection drug users was stated as futile, in other controlled clinical studies adherence and sustained biological response to antiviral treatment was slightly lower or similar to that reported in other groups of patients. In this review we describe the epidemiology, diagnosis and treatment of chronic hepatitis C, B and Delta in intravenous drug users.