Background: Ovarian hyper stimulation syndrome (OHSS), is an atypical reaction that women may experience in response to excessive hormones and often occurs during fertility treatments. So improving of women’ knowledge about this subject is most important aspect. The aim of this study was evaluate the effect of educational Program about Ovarian Hyper Stimulation Syndrome among Women Undergoing infertility treatment. Design: Quasi Experimental study design was used. Sitting: Study was conducted at In vitro fertilization department with its outpatient clinic at Ahmed Maher teaching hospital. Sample: convenient sample included 162 women. Tools two tools were used to data collection. The first tool structured interviewing questionnaire sheet was used to assess women`s general characteristics and infertility data - the second tool, women `s knowledge assessment sheet. It used to assess studied women knowledge regarding ovarian hyper stimulation syndrome, The main Results: only 13.2% of the studied women of study group had good knowledge regarding Ovarian Hyper Stimulation before implementing of educational program which improved to 73.5% and 74.7% good knowledge immediately and after three months of implementing of educational program respectively as p-value <0.01 for all variables.as regarding to control group where (98.6%) had poor knowledge in base line assessment, still (96.2%), (95.1) after routine care and end of three months of follow up had poor knowledge respectively with no statistical significant different compared to its level before. Conclusion The present study showed that, the knowledge of infertile women about ovarian hyper stimulation syndrome improved for women who received the educational program more than the control group who received routine care only. Recommendations: in the light of the finding of the study, the following recommendation is suggested increase women knowledge about ovarian hyper stimulation syndrome through health education and awareness become as a part of protocol infertility treatment.