The Authors present a case of umbilical endometriosis. A 38-year-old female presented with a nodule in her umbilical region. The nodule was brownish in colour and had enlarged slowly, reaching a size of 2 cm in diameter over the previous 7 months. The patient had no symptoms and there was no bleeding or pain during menstruation. The nodule was removed under local anaesthesia and histological examination was diagnostic for umbilical endometriosis. No recurrence occurred over a follow-up period of 7 months and the patient is in good general condition. Umbilical endometriosis is a very rare disease, but should be borne in mind in the differential diagnosis of umbilical lesions.