The aim of this study was to examine sexual inactivity and occurrence of selected sexually transmitted infections in relation to body mass index. We used data from two large Danish population-based cross-sectional studies conducted in 1991–1995 (HPV study: 6869 women, aged 22–32 years) and in 2004–2005 (Liva study: 19,484 women, aged 18–45 years). Data were collected using a structured interview and measured weight, height, high-risk human papillomavirus DNA, Chlamydia DNA for the HPV study and a structured questionnaire for the Liva study. Overweight and obese women were more likely to have had no lifetime sexual partner or no sexual partner in the last year, e.g., obese women had a threefold (95 percent CI: 1.95–5.04) odds ratio of having had no sexual partner in the last year compared to normal weight women. Additionally, overweight and obese women had a lower likelihood of genital warts and high-risk human papillomavirus infection. A similar tendency was found for self-reported Chlamydia, but not with presence of Chlamydia DNA. If higher likelihood of no lifetime or recent sexual partners among overweight and obese women reflects unmet sexual needs, it could give rise to concern because quality of sexual life is associated with general quality of life.