This is a report on a rare case of extragenital endometriosis with malignant degeneration. A woman of 40 years of age presented about 15 years after Caesarean section with a rapidly growing malignant node in the region of the scar from Pfannenstiel's incision, resulting in death from generalised metastasising after about 1 1/2 years despite intensive treatment. Histology revealed a typical clear-cell and partly tubular-cystic adenocarcinoma paramesonephroidal structure as part of an endometriosis. We believe this is an important case report, since it does not seem to have been reported in literature so far.