The aim of the study: was to evaluate the incidence of endometriosis in cases of unexplained infertility undergoing diagnostic laparoscopy at kasr EL Aini Hospital. Patients and methods: the study sample was 100 women in the child bearing periods with unexplained infertility who were planned to undergo diagnostic laparoscopy. Clinical assessment, laboratory investigations, imaging of the patients were collected.Results: our study , no doubt ,has some limits due to the nature of the study, and needs confirmation with randomized clinical trials, but the results suggest that the presence of endometriosis negatively influences fertility outcome. Conclusion: laparoscopy is the gold standard for definitive diagnosis of endometriosis. The incidence of endometriosis in unexplained infertility appears to range between 25% to 35%.