In literature an elevated number of isolated cases of endometriosis in post-laparoscopic scar or laparoscopic trocar tract are described. Actually no theory can completely account for endometriosis, and it is most likely that a combination of events is responsible for it. The case of a 37-year-old woman with a nodular mass in the right hypochondrium is reported. The nodule appeared after a laparoscopic cholecystectomy. Surgical excision was performed and microscopic analysis showed skeletal muscle and fibrous connective tissues with a typical glandular proliferation as in endometriosis. Endometrioma etiology is far to be cleared; the most practical and popular explanation is direct implantation. Our case may be explained according to this theory but it is difficult to achieve definitive conclusions due to the rarity of endometrioma and to the lack of information.