BACKGROUND: Although human papillomavirus (HPV) is the most common sexually transmitted infection, there are very scant data about the influence of this virus on the in vitro fertilization outcome. OBJECTIVES: To assess the presence of HPV in the cervico-vaginal fluid in relationship to the in vitro fertilization (IVF) outcome and to the concentration of selected cytokines, known to affect embryo implantation and gestation: granulocyte-macrophage colony stimulating factor (GM-CSF) and granulocyte colony stimulating factor (G-CSF). STUDY DESIGN: Cervico-vaginal samples were collected on the day of oocyte pick-up from 82 women. Vaginas were flushed with 50 mL of sterile water and 3 mL of fluid was collected. RESULTS: Twelve women (15%) were positive for HPV. Interestingly, among HPV(+) women live birth rate was about half of the rate in HPV(-) women, although the differences were not statistically significant due to the low number of cases. Cervico-vaginal samples of a sub-group of 29 (8 HPV(+) and 21 HPV(-)) women were analyzed for GM-CSF and G-CSF by ELISA. GM-CSF but not G-CSF was significantly lower in the cervico-vaginal fluid of HPV(+) than in HPV(-) women. CONCLUSIONS: Since GM-CSF plays an important role during pregnancy, the reduced levels of GM-CSF in the cervico-vaginal fluid of HPV(+) women might contribute to explain the reduced live birth rate observed in HPV(+) women