A young man presented with a 4-month history of progressive, bilateral tender gynecomastia and underwent a bilateral subcutaneous mastectomy without regard for a possible occult testicular tumor. Following the mastectomy, metastatic testicular cancer was discovered; the patient had an overlooked scrotal mass and a very elevated serum human chorionic gonadotropin tumor marker. The possibility of testicular tumor must be considered in any male, especially those in the younger age group, who present with gynecomastia.