With no more than 60 reported cases, tumors of the seminal vesicles are rare. Because of poor and nonspecific symptoms diagnosis is often very difficult. This report presents a case of a 56-year-old man with right renal agenesis and intermittent hematospermia and bilateral cystic masses of the seminal vesicles. Transrectal biopsies of the cystic lesion revealed a papillary clear cell adenocarcinoma. The patient underwent radical prostatectomy and pelvic lymphoadenectomy. Lymph node metastases were found on histological examination. The patient received 4 cycles of chemotherapy and pelvic radiotherapy. He remains disease free 21 months after surgery. Radiological imaging in patients with hematospermia and hematuria will allow disease detection at earlier stages. Immunohistochemistry and histomorphology can be used for differential diagnosis. Surgery with clear margins offers the best chance to cure. Hormonal and radio-chemotherapy have a role as adjuvant and palliative treatment.