Background. Women infected with human immunodeficiency virus (HIV) are disproportionately affected by human papillomavirus (HPV)–related anogenital disease, particularly with increased immunosuppression. AIDS Clinical Trials Group protocol A5240 was a trial of 319 HIV-infected women in the United States, Brazil, and South Africa to determine immunogenicity and safety of the quadrivalent HPV vaccine in 3 strata based on screening CD4 count: >350 (stratum A), 201–350 (stratum B), and ≤200 cells/µL (stratum C). Methods. Safety and serostatus of HPV types 6, 11, 16, and 18 were examined. HPV serological testing was performed using competitive Luminex immunoassay (HPV-4 cLIA). HPV type-specific seroconversion analysis was done for participants who were seronegative for the given type at baseline. Results. Median age of patients was 36 years; 11% were white, 56% black, and 31% Hispanic. Median CD4 count was 310 cells/µL, and 40% had undetectable HIV-1 load. No safety issues were identified. Seroconversion proportions among women at week 28 for HPV types 6, 11,16, and 18 were 96%, 98%, 99%, and 91%, respectively, for stratum A; 100%, 98%, 98%, and 85%, respectively, for stratum B, and 84%, 92%, 93%, and 75%, respectively, for stratum C. Conclusions. The quadrivalent HPV vaccine targeted at types 6, 11, 16, and 18 was safe and immunogenic in HIV-infected women aged 13–45 years. Women with HIV RNA load >10 000 copies/mL and/or CD4 count <200 cells/µL had lower rates of seroconversion rates.