Umbilical endometriosis is a very rare disease. We report a case of spontaneous umbilical endometriosis in a 36-year old female. Endometriosis was suspected because of the presence of the typical cyclic bleeding and swelling. Abdominal CT excluded the presence of other endometriotic localizations. The umbilical mass was widely excised together with the umbilicus, fascia and peritoneum. The ensuing defect was primarily closed without using prosthetic mesh. Postoperative recovery was uneventful. Histological examination of the specimen showed the presence of endometrial glands with a stromal component, compatible with the diagnosis of endometriosis. At one-year follow-up the results of surgery were satisfactory with no sign of endometriosis recurrence and or parietal defect occurrence. We suggest that surgical excision should be wide in order to prevent local recurrence, and prosthetic materials should not be used to repair the ensuing umbilical defect.