['To examine the relationships among dietary quality, weight status, and human immunodeficiency virus (HIV) infection in US adolescents and young adults.', 'This cross-sectional study was embedded in the Reaching for Excellence in Adolescent Care and Health cohort study of HIV-infected and HIV-uninfected, at-risk youth. Biochemical, clinical, and sociodemographic data were available. Dietary intake was collected using the Block Food Frequency Questionnaire and a modified Healthy Eating Index was calculated to measure diet quality.', 'Participants included 264 HIV-infected and 127 HIV-uninfected youth 13 to 23 years old (75.2% women, 67.3% African American/non-Hispanic, 20.5% Hispanic, 12.3% other) at 14 clinic sites.', 'Determinants of obesity and the modified Healthy Eating Index were tested using logistic and generalized linear regression.', 'About half (51.7%) of participants were overweight or obese. Obesity was positively associated with being a woman, living independently, watching television >or=3 hours per day, previous dieting, and being from the northeastern or southern United States. Youth who were HIV uninfected or HIV infected with CD4 + T cells >or=500 cells/microL had similar obesity rates; overweight (25%) and obesity (20%) was prevalent among women even with CD4 + T cells <200 cells/microL. The modified Healthy Eating Index score was 56.2+/-0.6, reflecting a diet needing improvement. HIV infection, watching television >or=3 hours/day, and being from the Chicago, IL, area were associated with a lower-quality diet.'] Are hIV-infected US youth at high risk of obesity and poor diet quality : a challenge for improving short- and long-term health outcomes?