Nipple trauma is a common complaint among breastfeeding women and it is one of the main reasons why some women decide to stop breastfeeding. It confronts nursing women 3-6 days after birth, especially primipara. Nipples become painful and start to show small cracks, which may bleed. This study aimed to test effect of olive oil application to nipples during late pregnancy on prevention of postpartum nipple trauma. The study findings revealed that 67% of the study sample didn't have nipple trauma with current breastfeeding after application of olive oil during late pregnancy (score 0) according to nipple trauma score assessment at 3rd day after starting breastfeeding and 65% of the study sample didn't have nipple soreness with current breastfeeding(score 0) according to nipple soreness rating scale assessment at the third day after starting breastfeeding, the study results also revealed that there is a highly significant relationship between period and frequency of application of olive oil to the nipples during late pregnancy and incidence of nipple trauma with breastfeeding (p=.000). This study concluded that Olive oil is effective for prevention and treatment of nipple trauma.