A papillary cystadenocarcinoma of epididymis with right paraureteral metastases in a 27-year-old man is presented. It was a 14x13x8 cm cystic mass in the right testicular adnexa which had been noted for more than 10 years. From its prolonged clinical course and the morphological findings, this tumor was thought to be a malignant transformation from previously benign lesion--papillary cystadenoma. Review of the literature disclosed that it is a very rare malignancy arising from the testicular adnexa.