OBJECTIVES: To describe factors associated with incident sexually transmitted infections (STI) in a population-based sample of women in Goa, India. METHODS: A random sample of women aged 18-45 years was enrolled in Goa from November 2001 to May 2003. All subjects who consented to participate and completed the recruitment procedure were interviewed six and 12 months after recruitment. Incident chlamydia, gonorrhoea or trichomoniasis from vaginal and/or urine specimens were detected using a commercial polymerase chain reaction and the InPouch TV Culture Kit. RESULTS: Of the 2180 women followed up, 64 had an incident STI (incidence of 1.8% in the first six months, and 1.4% in the second six months). Incident STI was associated with low socioeconomic status, marital status, and with concurrent bacterial vaginosis. Incidence was highest among women who were married and exposed to sexual violence (10.9%), were concerned about their husbands' affairs (10.5%), or were separated, divorced or widowed women (11.0%). CONCLUSIONS: Socially disadvantaged women are at increased risk of STI in this population. Sexual intercourse outside marriage was rarely reported in this population, and women are at risk of becoming infected within marriage, especially those with sexual violence. This highlights the vulnerabilities of socially disadvantaged married women in India, and the need for healthcare professionals to screen STI patients for violence, and provide the necessary support. The results also stress the importance of effectively diagnosing and treating married men with STI and promoting safer sex within marriage.