Anemia is a common manifestation of HIV infection, occurring in approximately 30% of patients with asymptomatic infection and in as many as 75% to 80% of those with AIDS. Anemia has been associated with decreased quality of life and decreased survival. We performed a cross-sectional study nested within a multicenter prospective cohort study to describe the prevalence of anemia in 2056 HIV-infected and 569 HIV-negative women as well as to define the demographic, clinical, immunologic, and virologic correlates of anemia among HIV-infected women. A total of 37% of HIV-positive women and 17% of HIV-negative women had hemoglobin levels < 12 g/dl (p< .001). Factors associated with anemia in HIV-positive and HIV-negative women included mean corpuscular volume (MCV) < 80 fl (p< .001) and black race (p< .001). Among HIV-infected women, multivariate logistic analyses revealed that African American race (p< .0001), MCV < 80 fl (p< .0001), CD4 count < 200 per microliter (p< .0001), higher HIV RNA in plasma (p= .02), current use of ZDV (p= .01), and history of clinical AIDS (p= .004) were all independent predictors of anemia. These data indicate that worsening parameters of HIV disease are associated with anemia among HIV-infected women. Black women and women with low MCV values are at increased risk for anemia independent of HIV status.