A 25-year-old single man presented with a mass in the right testis. He had a history of left radical orchiectomy for testicular cancer. Magnetic resonance imaging (MRI) and ultrasonography demonstrated a tumor (2 cm in diameter) within the right tests. The patient underwent right partial orchiectomy. Histological examination revealed typical seminoma of the right testis. He is alive with no evidence of disease recurrence at 18 months after surgery, and did not need androgen substitution.