Health-related quality of life (HRQOL) is diminished in patients infected with both hepatitis C virus (HCV) and human immunodeficiency virus (HIV), but the effect of HIV/HCV coinfection on HRQOL is unknown. We compared the HRQOL of urban HIV/HCV coinfected patients with that of patients infected with either HCV or HIV alone. We then compared the 3 groups with a US population sample, adjusting for demographic characteristics. HRQOL for the group of HIV/HCV coinfected patients was statistically similar to that of HRQOL in patients with either HCV or HIV alone, but the 3 groups had a significantly decreased HRQOL than did the adjusted US population. Using multivariate techniques, we determined that age, unemployment, injection drug use, and depression were associated with impaired HRQOL. These findings underscore the importance of a multidisciplinary approach to the treatment of these patient populations.