The objective of this paper is to evaluate the effect of mode of delivery on postpartum sexual functioning in primiparous women. A total of 248 primiparous women were recruited into this study. One hundred fifty-six delivered spontaneously with mediolateral episiotomy and 92 had elective cesarean section. Sexual function was evaluated by the Female Sexual Function Index, a validated questionnaire separately evaluating desire, lubrication, orgasm, satisfaction, and pain. Subjects were questioned relating their pre-pregnancy experiences during the first antenatal visit when the pregnancy was not more than six gestational weeks. The test was repeated 6 months postpartum. Statistical evaluation was carried out by SPSS for Windows v.11. In the vaginal delivery with mediolateral episiotomy group, there were significant decreases in the scores 6 months after delivery when compared to scores before pregnancy (p<0.001). In the cesarean section group, no difference was observed between pre-pregnancy and postpartum scores (p>0.05). When the two groups were compared, there was a significant difference between 6 months postpartum scores (p<0.001). Not only pain, but also other important aspects of sexual function, such as arousal, lubrication, orgasm, and satisfaction are affected by performing mediolateral episiotomy during vaginal delivery, well beyond the puerperal period. Concerning its effects on postpartum sexual functioning, a policy of restricting mediolateral episiotomy use should be adopted.