Regardless of the nontreponemal test used for the screening and diagnosis of syphilis, biological false-positive results (BFPs) are documented in 1%-2% of all cases. An association between BFPs and human immunodeficiency virus (HIV) infection in men has been suggested. We conducted a cohort study to determine whether a similar association between HIV seropositivity and BFPs exists for women. Among 156 HIV-seropositive women, 9 (5.8%) had a BFP for syphilis. Among 633 HIV-seronegative women, only 1 (0.2%) had a BFP. When the 25 HIV-seropositive patients and 55 HIV-seronegative patients with reactive rapid plasma reagin tests and microhemagglutination assays for antibodies to Treponema pallidum were excluded from the calculations, 6.9% and 0.2% of HIV-seropositive and HIV-seronegative women, respectively, had BFPs (P < .001; odds ratio, 39.45; 95% confidence interval, 6.4-879.0). An association was found between injection drug use and BFPs for the population of HIV-infected women but did not entirely account for the differences between this group and the HIV-seronegative group.