Staff in drug treatment programs are in an optimal position to support the hepatitis C related needs of their patients. To do so effectively, however, staff need to have accurate information about the hepatitis C virus (HCV). This article examines the HCV knowledge of staff (N = 104) in two drug-free and two methadone maintenance treatment programs (MMTPs) in the New York metropolitan area. Five of 20 items on an HCV Knowledge Assessment were not answered correctly by the majority of the participating staff, and total scores on the Assessment averaged 70%, 71%, and 45% among the medically credentialed staff, non-medically credentialed staff in the MMTPs, and non-medically credentialed staff in the drug-free programs, respectively. The majority of those in the latter group had never participated in a training specifically devoted to HCV. Results suggest the need for effective HCV-related training for all staff in drug treatment programs. (Contains 3 tables.)