Objective: To obtain histologic confirmation of lesions suspected of endometriosis at laparoscopy. Design: Prospective clinical study. Setting: Patients in an academic hospital. Patient(s): Women of reproductive age who complained of chronic pelvic pain. Intervention(s): A total of 122 biopsies were obtained from 54 patients undergoing laparoscopy, after exclusion of other potential causes of pelvic pain. Main Outcome Measure(s): Lack of consistency between laparoscopic and histologic diagnosis of endometriosis, in particular for minimal/mild stages. Result(s): Endometriosis was confirmed by histology in 54% of the excised lesions. Diagnosis was more often confirmed among classic lesions than for all atypical lesions considered together. The histologic diagnosis of fibrosis was the most common among those biopsies, which lacked the presence of endometriosis. The revised American Fertility Association (AFS) scores before and after histologic confirmation differed significantly. In particular, 20 patients in either revised AFS class Ⅰ or Ⅱ were down-graded to stage 0. No single anatomical site turned out to be particularly prone to misdiagnosis at laparoscopy, in comparison to the other sites. Conclusion(s): These results confirm the need of histologic confirmation to obtain a diagnosis of endometriosis. However, the clinical impact of such findings remains a matter of debate. Objective: To obtain histologic confirmation of lesions suspected of endometriosis at laparoscopy. Design: Prospective clinical study. Setting: Patients in an academic hospital. Patient (s): Women of reproductive age who complained of chronic pelvic pain. Intervention (s): A total of 122 biopsies were obtained from 54 patients undergoing laparoscopy, after exclusion of other potential causes of pelvic pain. Main Outcome Measure (s): Lack of consistency between laparoscopic and histologic diagnosis of endometriosis, in particular for minimal / mild stages. s): Endometriosis was confirmed by histology in 54% of the excised lesions. Diagnosis was more often confirmed among classic lesions than for all atypical lesions considered together. The histologic diagnosis of fibrosis was the most common among those biopsies, which lacked the presence of The revised American Fertility Association (AFS) scores before and after histologic confirmation differed significantly. In parti cular, 20 patients in either revised AFS class I or II were down-graded to stage 0. No single anatomical site turned out to be particularly prone to misdiagnosis at laparoscopy, in comparison to the other sites. Conclusion (s): These results confirm the need of histologic confirmation to obtain a diagnosis of endometriosis. However, the clinical impact of such findings remains a matter of debate.