Rhabdomyomas are benign tumors in which at least some cells are differentiated as skeletal muscle cells with cytoplasmic cross-striations. Extracardiac adult rhabdomyoma is an extremely uncommon benign neoplasm that usually involves the head and neck region. Rare cases have been reported to involve other sites of the body including mediastinum. We report the fourth case of mediastinal adult rhabdomyoma.