A case of cervical adenocarcinoma arising in diffuse mesonephric hyperplasia is presented. The hyperplastic and neoplastic tubules showed focal endocrine cell differentiation. Endocrine cells stained with the Grimelius technique, and were immunoreactive for chromogranin and serotonin. Antisera to additional specific hormones were negative. The natural history of this rare tumor is uncertain; the patient presented in this report is free of disease at 10-year follow-up.