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)