Introduction: Aim of the study was to determine the seroprevalance of HIV, HBS and Syphilis co-infection if any present and the associated risk factors in a tertiary care center of Mangaluru. Materials and Methods: The study was conducted on 500 women attending antenatal checkups at A.J. Institute of Medical Sciences, Mangaluru. They were screened for HIV, HBV and Syphilis and were requested to provide socio-demographic and obstetric data following appropriate counselling and ethical clearance. Results: The seropevalence of HIV, HBV infection and Syphilis were found to be 2.6%, 3.4% and 0.2% respectively. Low literacy levels, early initiation of sexual activity, low per capita income were the most commonly associated risk factors. Conclusion:Sexually transmitted diseases and its complications are a significant part of health challenges the public face today. Most common among the sexually active group, it is a major issue among the reproductive age group as the infection can be transmitted vertically.