The extent to which human immunodeficiency virus (HIV-1) infection impacts on the ability to mount an effective immune response to HPV is unknown, but is relevant in planning HPV vaccine strategies for HIV-1 infected individuals. This longitudinal study investigated changes shortly after HIV-1 seroconversion on cervical HPV types and HPV-16 antibody responses in serum and at the cervix of female sex workers. Typing of HPV DNA from cervical cells was done prior to HIV-1 seroconversion and within 1 year and greater than 2 years after HIV-1 seroconversion. Antibody determinations on serum and cervico-vaginal rinse samples were by HPV-16 virus-like particle-based, enzyme-linked immunosorbent assay. Of 104 women tested, 40 (38.4%) became HIV-1 seropositive (HIV-positive) during the course of the study. Shortly after HIV-1 seroconversion a significant increase in multiple (>1) HPV infection (OR 4.0, 95% CI 1.3-11.9) was observed compared with HIV-1 seronegative (HIV-negative) women and certain changes in HPV type infection. HIV-1 seroconversion resulted in a reduced prevalence of serum HPV-16 IgA and cervico-vaginal IgA and IgG but an increased prevalence of serum HPV-16 IgG. All HIV-positive women had been exposed to HPV-16 as all displayed serum HPV-16 IgG. Serum HPV-16 responses were maintained at a high magnitude in the presence of HPV-16 infection irrespective of HIV infection, but decreased in the absence of HPV-16 infection. In conclusion, HIV-1 seroconversion in sex workers rapidly increased cervical HPV infection and caused a reduced ability to produce cervical HPV-16 antibodies but a continued ability to generate serum IgG antibodies.