Despite the prevalence of syphilis worldwide, little is known about its manifestations when associated with other Sexually Transmitted Infections (STI), specifically the Human Papilloma Virus (HPV). Current epidemiological studies show that there is a high incidence of both diseases in ambulatory clinics all over Brazil. This study aims to estimate the incidence of syphilis - HPV co-infections, among patients from the STI ambulatory clinic at the Santa Casa da Misericórdia Hospital, Rio de Janeiro, Brazil. Two-hundred and seven patients were seen in the clinic between March and December 2005, of which 113 (54.6%) sought care for an HPV infection. Blood samples were taken from all patients to check syphilis serology using the flocculation and the non-treponemic test or VDRL (Venereal Disease Research Laboratory) and the TPHA (Treponema Pallidum Hemagglutination Assay) treponemic and confirmatory method. Of the 207 patients, 113 (54.6%) consulted referring to HPV as their primary complaint, and of these, 18 (15.9%) also presented with positive syphilis serology, demonstrating a high incidence of coinfection. The average age of the patients varied between 20 and 25 years, 203 (98.1%) were male and 4 (1.9%) were female. The predominance of the male sex in this sample confirms the profile usually treated in STI clinics across the country, and the age range is that of typically high sexually activity. Conclusion: The results demonstrated the need for a differentiated examination of all STD patients.