Genotypic frequencies differed significantly between women with and without endometriosis, with a higher prevalence of the non-GG genotype (GT, TT) in the endometriosis group compared to the control group./These findings indicate that the T allele, which encodes aspartic acid, of the Glu298Asp polymorphism in NOS3 may be linked to advanced stage endometriosis in the Korean population. This evidence concerns the gene NOS3 and endometriosis.