Although high prevalence of hepatitis C virus (HCV) in correctional institutions has been established, data are sparse regarding the comorbidities of hepatitis B virus (HBV), HCV, and human immunodeficiency virus (HIV), all of which may complicate the management of HCV. This study sought to estimate the prevalence and correlates associated with HCV prevalence among entrants into the Maryland Division of Correction and the Baltimore City Detention Center. Participants included all newly incarcerated entrants between January 28 and March 28, 2002. Excess sera with identifiers removed from samples drawn for routine syphilis testing were assayed for antibodies to HIV and HCV and for HBV surface antigen and surface and total core antibodies. Separately, all HIV-positive specimens were tested using the serological testing algorithm for recent HIV seroconversion. Of the 1,081 immates and 2,833 detainees, reactive syphilis serology was noted in 0.6% of the combined population; HIV seroprevalence was 6.6%; HCV prevalence was 29.7%; and 25.2% of detainees and prisoners had antigen or core or surface antibodies to HBV. A multivariate analysis of predictors of HCV positivity indicated that detainees, women, whites, older age groups, those who were HIV seropositive, and individuals with past or present infection with HBV were significantly more likely to be positive for HCV. These data indicate that hepatitis C remains an important public health concern among entrants to jail and prison and is complicated with coinfections that need to be addressed for effective treatment.