To study factors associated with anemia and its effect on survival in HIV-infected persons treated with modern combined antiretroviral therapy (cART), we characterized the prevalence of anemia in the Veterans Aging Cohort Study (VACS) and used a candidate gene approach to identify proinflammatory gene single nucleotide polymorphisms (SNPs) associated with anemia in HIV disease. The study comprised 1597 HIV+ and 865 HIV- VACS subjects with DNA, blood, and annotated clinical data available for analysis. Anemia was defined according to World Health Organization criteria (hemoglobin < 13 g/dL and < 12 g/dL in men and women, respectively). The prevalence of anemia in HIV+ and HIV- subjects was 23.1% and 12.9%, respectively. Independent of HIV status, anemia was present in 23.4% and 8% in blacks and whites, respectively. Analysis of our candidate genes revealed that the leptin -2548 G/A SNP was associated with anemia in HIV+, but not HIV-, patients, with the AA and AG genotypes significantly predicting anemia (P < .003 and P < .039, respectively, logistic regression). This association was replicated in an independent cohort of HIV+ women. Our study provides novel insight into the association between genetic variability in the leptin gene and anemia in HIV+ individuals. (Blood. 2011;118(20):5401-5408)