OBJECTIVES: Endometriosis is defined as the presence of endometrial glands and stroma outside of the uterine cavity. It is a disease of pre-menopausal women, and can manifest in mild to severe pain symptoms which can severely affect a woman's quality of life. Gold standard for diagnosis has been to obtain peritoneal biopsies for pathologic presence of ectopic endometrial tissue. Based on this standard, we questioned if there is a correlation between microscopic endometriosis in patients with pelvic pain and benign-appearing pelvis on laparoscopy. MATERIALS AND METHODS: A retrospective chart review was performed on all patients, with pelvic pain, who underwent peritoneal biopsy surgeries at our institution between January 1, 2007 to September to 9, 2009. Pathology data was collected; presence of endometriosis and site of the biopsy were recorded. RESULTS: Of 247 patients, 17 were found to have benign-appearing pelvis, on laparoscopy, with no gross visualization of endometriosis. Of these 17 patients, 4 were found to have biopsy site positive for endometriosis, resulting, in 23% of those with normal-appearing pelvis to have pathologic evidence of endometriosis. CONCLUSION: Given this initial data, it may be possible to extrapolate that peritoneal biopsies should be performed in all patients undergoing surgical evaluation for pelvic pain.