Approximately 1 in 4 individuals infected with the human immunodeficiency virus (HIV) in the United States is coinfected with the hepatitis C virus. Both conditions increase the risk for the development and progression of kidney disease. The effect, however, of coexisting HIV and hepatitis C infection on the spectrum and progression of kidney disease is not well known. To compare the clinical features, histopathologic kidney diagnoses, and proportion of individuals progressing to end-stage kidney disease (ESKD), we reviewed the clinical records of HIV-infected individuals with and without hepatitis C coinfection who underwent ultrasound-guided percutaneous kidney biopsies between February 7, 1995, and March 30, 2009.Of the 249 HIV-infected individuals included in this study, 58% were coinfected with hepatitis C. Coinfected individuals were older (mean age, 46 ± 7 vs. 44 ± 10 yr, respectively; p < 0.01) and more likely to have used illicit drugs (85% vs. 14%, respectively; p < 0.01) compared to HIV-infected individuals without hepatitis C. HIV-associated nephropathy was the most common histopathologic diagnosis in both groups. Immune-complex glomerulonephritides (ICGNs), including lupus-like nephritis, postinfectious glomerulonephritis, membranous glomerulopathy, membranoproliferative glomerulonephritis, IgA nephropathy, and nonspecific ICGNs, occurred more frequently in individuals coinfected with hepatitis C than in those not coinfected (22% vs. 11%, respectively; p = 0.02). Although the proportion of those who died was similar between the 2 groups, hepatitis C coinfection was independently associated with a greater risk of progression to ESKD (hazard ratio, 1.81; 95% confidence interval, 1.09-2.99; p = 0.02).The current study demonstrates that coinfection with hepatitis C in individuals infected with HIV predisposes these individuals to immune-complex glomerulonephritides and is associated with increased risk of ESKD in the biopsied population.