Introduction: Due to non-availability of a good non-invasive or semi-invasive test for diagnosing endometriosis, there is a substantial time delay between the onset of symptoms and surgically confirmed endometriosis. Development of a simple non-invasive or semi-invasive diagnostic method can greatly help to reduce this delay and prevent severe morbidity in minimal to mild endometriosis which cannot be diagnosed clinically or by ultrasonography. Aim: To evaluate the role of nerve fibre detection in endometrial biopsy for diagnosing endometriosis Materials and Methods: In this observational study, detection of endometrial nerve fibres in endometrial biopsy in women undergoing laparoscopy/laparotomy for pelvic pain or infertility was done using polyclonal rabbit anti-protein gene product 9.5 (Dako, Australia). The results were compared between women who has laparoscopic/laparotomy visualisation of endometriotic lesions with those who don't have endometriotic lesions. Women with visual evidence of endometriosis in laparoscopy/laparotomy were taken as cases (n=32). Women without evidence of endometriosis in laparoscopy/laparotomy were taken as controls (n=29). Presence of endometrial nerve fibre was compared between women with and without evidence of endometriosis. Presence of endometrial nerve fibres and its association with painful symptoms, history of hormonal therapy, endometrial histopathology and stages of endometriosis was analysed. Results: Endometrial nerve fibres were detected in the functional layer in 21.8% of the endometriosis patients and no nerve fibres were detected in the control group. There was no significant association between endometrial nerve fibres in endometriosis and presentation of painful symptoms, history of hormonal therapy, endometrial histopathology and stages of endometriosis. Sensitivity of detecting endometriosis by the presence of nerve fibres in endometrial nerve biopsy specimen was 21.8% and specificity was 100%. Conclusion: Endometrial nerve fibre assessment for identifying endometriosis in women undergoing laparoscopy/laparotomy using routine endometrial sampling and immunohistochemical analysis was found not to be sensitive for the diagnosis of endometriosis.