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 post partum nipple trauma .Subjects and methods (One group time series) quasi-experimental design was adopted in this study to achieve the stated aim. Purposive sample of 100 pregnant women who met inclusion criteria were recruited for the study from antenatal clinic of Obstetrics and Gynecology Hospital. Data were collected through 4 tools (I) Maternal structured interview questionnaire, (II) Nipple soreness rating scale (NSR),(III) Nipple trauma score (NTS), (IIII) WHO B-R-E-A-S-T Feed observation form. Procedures were carried out through four phases Interviewing, Pretest, Intervention, Posttest. Results The study finding revealed that 67% of the study sample had no nipple trauma (score 0) according to nipple trauma score assessment at 3rd day after starting breastfeeding, it was also revealed that their is a highly significant relation 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. The study recommended that application of olive oil during late pregnancy is beneficial in prevention of nipple trauma.