Knowledge about the determinants of female sexual function in breastfeeding women is limited. A total of 355 breastfeeding women completed the Female Sexual Function Index (FSFI) and the Qol-8 quality of life questionnaire. FSFI scores decreased in the first six months of breast feeding. There was a positive relationship between FSFI scores and the importance of sex, level of communication, income, quality of life, and receiving brief sexual counseling.