Aim: We report a case of a mixed clear cell and endometrioid carcinoma arising in parietal endometriosis. Methods: A 46-year-old woman presented a second recurrence of parietal endometriosis. An extensive surgical resection of the tumor was then carried out. Results: Histological analysis revealed heterogeneous tissues including clear cell and endometrioid carcinoma fields arising from a large benign endometriosis lesion. Despite chemotherapy, the patient died 6 months after the diagnosis. Conclusions: Clear cell carcinoma and endometrioid carcinoma have been rarely found in parietal endometriosis. Clinicians should learn to suspect a cancerous transformation of a parietal endometriosis, when rapid recurrence and extensive development are observed.