Globally, approximately 90% of new hepatitis C infections are attributed to injection drug use, but there is a continuing reluctance to treat injection drug users (IDUs). There is evidence that a sizeable proportion of IDUs who begin hepatitis C treatment achieve a sustained virological response (SVR). In chronic hepatitis C treatment trials, the SVR rate among IDUs appears to be comparable to rates among non-IDUs; in trials prescribing pegylated interferon plus ribavirin, the median rate of SVR among IDUs was 54.3% (range, 18.1%-94.1%), compared with 54%-63% in the large treatment trials. Few trials of acute hepatitis C treatment report on outcomes in IDUs; however, among these trials, the SVR among IDUs was 68.5% (n=89), compared with 81.5% among non-IDUs (n=65). Additional studies are required to determine the optimal circumstances for treatment (e.g., enrollment in drug treatment, the requirement of a period of abstinence from injection drug use, or the establishment of multidisciplinary treatment programs).