Nitrite/nitrate levels were significantly elevated in women with endometriosis. Although not statistically significant, NO levels appeared higher in ectopic compared to eutopic endometrial tissues. Additionally, there was a modest rise in endometrial iNOS protein levels in women with endometriosis compared to those without./Increased levels of NO and NOS in the endometrial tissues of women with endometriosis suggest a potential involvement of NO in the disease’s pathogenesis. Here, NOS1 is linked to endometriosis.