Background and Rationale: premenstrual syndrome (PMS) may have a considerable impact on women's QOL. Evening primrose oil as an herbal treatment has a role in alleviating premenstrual syndrome-related symptoms, CAM therapies (specifically Herbs) have gained popularity. Objectives: Evaluate effectiveness of primrose oil in management of premenstrual syndrome -related symptoms. Material and Methods: The study was Single- blinded placebo controlled study. Females in childbearing period with premenstrual syndrome, mild, moderate or severe symptom were enrolled from Primary health care unit (ELDARASSA family health center at Cairo). PMS Self Evaluation Questionnaire (PEQ) was used for rating symptoms before and after intervention. For 4cycle (1cycle baseline and 3 cycle treatment).Primary outcome Results: Results show substantial health improvement upon using primrose oil. This study showed that there was significant difference between women in the study group and control group. Regarding improvement after treatment in psychological symptoms: was highly significant in depression symptom with P value (.001), and statistically significant in anxiety with P value (.012). For physical symptoms: breast tenderness highly significant with P value (.000) and acne statistically significant with P value (.012).While the difference in the rest of symptoms was not significant. The mean of the total PMS score among studied group according to PMS Self Evaluation Questionnaire (PEQ) before intervention was 25.7 + or-7.7 and it turned to be 18.1+ or-6.5 after intervention and this difference was statistically highly significant. Conclusion: Evening primrose oil has been found to significantly improve subjective measures of premenstrual syndrome symptoms in frequency and severity decreasing the climacteric distress among females in childbearing period in this single-blinded placebo controlled study.