Background: Previous studies indicated an association between endothelial nitric oxide synthase (eNOS) activity and maintenance of pregnancy, but it is rather controversial whether polymorphisms of the gene encoding for eNOS are associated with recurrent spontaneous abortions (RSA). Endothelium-derived nitric oxide (NO) is synthesized from L-arginine by (eNOS) encoded by the eNOS gene on chromosome 7. The effects of the eNOS polymorphisms on the risk of RSA are conflicting.Objectives:To investigate whether presence of maternal polymorphism GLU298ASP in exon 7 of the eNOS gene increase the risk of RSA in Egyptian women.Patients and Methods:100 women, mean age of 27 years (range 20-35) were included in the cases group. Who had at least three RSA before 20th weeks of gestation, with the same partner and at least one live birth .The control group consists of 100 women, same age range and with no history of abortions or complicated pregnancy. All cases and controls were investigated for the polymorphism by using the PCR-RFLPs method to genotype all candidates.Results: Frequency of GG genotype 50% in cases & 67% in control group .Heterozygous GT frequency was 46 % in cases and 26 % in control (odds ratio 2.37 and P value 0.005). Homozygous TT was 4% in the cases and at 7 % in control (odds ratio of 0.77 and P value of 0.682). GG genotype Vs GT and GG (odds ratio 2.03 and P value 0.015). Cases with TT genotype were more susceptible to abortion at older age with a mean of 29 years ± 4.76 (P value 0.020).Conclusion:In conclusion, (eNOS) Glu298ASP polymorphism was found to be associated with increased risk of RSA in this sample of Egyptian women.