A 25-year-old man presented with acute pain in the right lower quadrant of the abdomen and a locally palpable mass. The tumour was extirpated together with the right seminal vesicle, adjacent ureter and bladder wall. The histologic diagnosis was extraskeletal Ewing's sarcoma. No tumour tissue was seen within the seminal vesicle. Intensive postoperative chemotherapy was given and at 18-months follow-up the patient was apparently tumour-free.