Persons chronically infected with hepatitis C virus (HCV), some of whom may be coinfected with HIV and human T-lymphotropic virus type II (HTLV-II), are at high risk for end-stage liver disease (ESLD). We evaluated whether ESLD death was associated with premorbid HCV RNA level or specific HCV protein antibodies among persons with or without HIV/HTLV-II coinfection in a cohort of 6,570 injection drug users who enrolled in 9 US cities between 1987 and 1991. We compared 84 ESLD descendents and 305 randomly selected cohort participants with detectable HCV RNA, stratified by sex, race, HIV, and HTLV-II strata. Relative hazard (RH) of ESLD death was derived from the proportional hazard model. Risk of ESLD death was unrelated to the intensity of antibodies against the HCV c-22(p), c-33(p), c-100(p), and NS5 proteins, individually or combined, but it increased with HCV RNA level (RH(adj) = 2.26 per log(10) IU/mL, 95% CI: 1.45-5.92). The association between HCV RNA level and ESLD death remained significant after adjustment for alcohol consumption (RH(adj) = 2.57 per log(10) IU/mL, 95% CI: 1.50-8.10). Deaths from AIDS (n = 45) and other causes (n = 43) were unrelated to HCV RNA (RH(adj)= 1.14 and 1.29 per log(10) IU/mL, respectively). HIV infection was not associated with ESLD risk in multivariate analyses adjusted for HCV RNA. Men had an increased risk of ESLD death in unadjusted analyses (RH = 1.92, 95% CI: 1.15-3.56) but not in multivariate analysis (RH(adj) = 0.98, 95% CI: 0.48-2.88). Non-black patients were at increased risk for ESLD death (RH(adj)= 2.76, 95% CI: 1.49-10.09). In conclusion, HCV RNA level is a predictor of ESLD death among persons with chronic HCV infection.