We herein describe an unusual late radiation-related complication requiring surgery in a 60-year-old male affected by anal epidermoid carcinoma. The patient presented with obstructed defecation and ulcerated perianal lesions. The perianal biopsies were positive for anal squamous carcinoma. Transanal diagnostic investigations could not be performed because of anal stenosis. Computed tomography detected left inguinal lymphadenopathy and a nonhomogeneous presacral mass, infiltrating the rectal wall, the coccyx, and the sacrum. The patient underwent a colostomy, infusion of cisplatin and 5-fluorouracil, and irradiation of the pelvis, perianal region, and inguinal lymph nodes. In June 1997 the patient complained of the onset of continuous pain at the genitalia, and for penis necrosis he underwent penis amputation. The histologic examination was conclusive for postradiotherapy thrombosis. This complication could strengthen the hypothesis of vasculoconnective damage as the origin of long-term effects of radiotherapy. Probably the minimal dose in transit volume could not be achieved. Careful evaluation in choosing the treatment scheme is necessary if different options are available.