Total surgical excision of the tumor is considered to be the only hope in treatment of malignant mesenchymal tumors. The roles of radiotherapy and/or chemotherapy have not yet been established. We report here a case of metastatic gastrointestinal stromal tumors with a dramatic long duration of response after treatment with concurrent radiotherapy and imatinib mesylate. The patient had a long-term complete response at the radiotherapy region with concomitant imatinib therapy although previous metastatic sides persisted with partial response.