Two adult patients with rhabdomyosarcoma of the infratemporal fossa region were evaluated by computed tomography and magnetic resonance imaging both before and after treatment. Successful treatment accompanied by reduction of the tumor mass as a result of chemotherapy was demonstrated in one patient. In the other patient a subsequent increase in the tumor mass was documented. Information on not only the size but also the internal architecture of the tumor may be useful when tumor response to therapy is being investigated. Magnetic resonance imaging is recommended as a method for outcomes evaluation in adult rhabdomyosarcoma cases.