['To quantify the expression of transforming growth factor beta1 in nerve fibers in endometriotic lesions and to correlate it with dysmenorrhea and appearance of endometriotic implants.', 'Prospective comparative study.', 'University hospital.', 'Peritoneal endometriotic specimens obtained from 35 patients diagnosed with endometriosis were compared with biopsies of normal peritoneum from 10 patients without endometriosis.', "Endometriosis-associated dysmenorrhea for each patient was evaluated before surgery using a 10-point visual analog scale, which was followed by a laparoscopic staging of the patient's endometriosis.", 'Immunohistochemical analysis of the peritoneal endometriotic specimens evaluated the maximal intensity of staining (INTMMAX) of TGFbeta1, defined as higher staining intensity found within a selected structure.', 'When the nerve fibers of endometriotic lesions were compared with those of normal peritoneum, statistically significant differences were found in the INTMMAX of TGFbeta1. Greater TGFbeta1 INTMMAX was found in red lesions and deep endometriotic foci than in black lesions and normal peritoneum. A statistically significant relationship was found between the TGFbeta1 INTMMAX score and dysmenorrhea; a relationship also was found to the color of the lesions.'] Is expression of transforming growth factor beta1 in nerve fibers related to dysmenorrhea and laparoscopic appearance of endometriotic implants?