Intercourse during menses is an acceptable sexual behavior that is practiced by 3-30% of sexually active women. This pattern of sexual behavior may contribute to transmission of some sexually transmitted disease. Yet, intercourse during menses is probably not associated with increased risk for pelvic inflammatory disease. The above-mentioned susceptibility for increased risk for sexually transmitted disease in women engaged in sexual intercourse during menses could be explained by the sexual behavior itself and/or by hampered response of innate immune system during menses. Still, while counseling couples about intercourse during menses, its potential advantages should be weighed against possible disadvantages.