Since the introduction of highly active antiretroviral therapy (HAART) and the subsequent increased life expectancy in HIV-infected persons, non-HIV-related diseases have become an important cause of morbidity and mortality. This cross-sectional study reports the prevalence of overweight and obesity, and sociodemographic, psychological, and substance use-related risk factors for elevated body mass index (BMI) among 2157 HIVseropositive (HIVþ) in comparison to 730 HIV-seronegative (HIVÀ) participants in the Women's Interagency HIV Study (WIHS). Separate univariable and multivariate linear regression analyses were completed for HIVþ and HIVÀ women. Our study revealed a similar proportion of obesity (body mass index [BMI] !30) among HIVþ (33%) and HIVÀ women (29%) ( p ¼ 0.12), as well as comparable median BMI (HIVþ: 26.1 versus HIVÀ: 26.7, p ¼ 0.16). HIVþ compared to HIVÀ women, respectively, were significantly ( p < 0.01) older (median ¼ 35.6 versus. 32.5), but similar ( p ¼ 0.97) by race=ethnicity (57% African American, 28% Hispanic, and 15% white for both). In multivariate models for both HIVþ and HIVÀ women, African American race=ethnicity was significantly ( p < 0.05) associated with higher BMI, while higher quality of life score and illicit hard drug use were associated with lower BMI. Additionally, smoking, alcohol use, markers of advanced HIV infection (AIDS diagnosis, elevated HIV viral load, low CD4 count), and a history of antiretroviral therapy use (ART) were also associated with lower BMI among HIVþ women. In conclusion, risk factors for elevated BMI were similar for HIVþ and HIVÀ women in the WIHS. For HIVþ women, all markers of advanced HIV infection and ART use were additionally associated with lower BMI.