PURPOSE: This study aimed to evaluate the preliminary treatment results of fractionated stereotactic radiotherapy (FSRT) for metastatic brain tumors. MATERIALS AND METHODS: Between August 1997 and December 1998, frameless FSRT was performed in 11 patients with metastatic brain tumor (1S lesions). Primary sites were lung in 7 patients, breast in 2, stomach in 1, and malignant melanoma in 1, All patients received 30-36 Gy/10-20 fx external beam irradiation to whole brain. Eight patients received FSRT for 1 lesion, one for 2 lesions, and two for 4 lesions. Fractionation schedule was 25 Gy/5 fx in 11 lesions, 18 Gy(1 fx in 3, 30 Gy/5 fx in 2, 15 Gy/5 fx in 1. Mean tumor volume was 7.0 cc (0.39~55.23 cc). Multiple-arc FSRT was delivered to 16 lesions and conformal FSRT through irregular ports shaped to tumor profile to 2 lesions. RESULTS: No patient experienced any acute side reaction from FSRT. Follow-up radiologic evaluation was available in 9 patients. Six of nine patients achieved the complete response, but two showed the partial response and one showed no response on follow-up radiologic studies. Among six patients with complete response, 5 patients survived from 5 to 15 months and showed no evidence of metastatic brain d#isease clinically and/or radiologically at last follow-up. Among two patients who did not have radiologic evaluation, one showed clinically complete response until death and the other died just after FSRT caused by intercurrent disease. One patient with no response radiologically survived 7 months and showed nearly complete disappearance of clinical symptom with stable status radiologically, CONCLUSION: Initial experience in this study suggests that the external beam irradiation to whole brain with 30 Gy/10 fx followed by FSRT with 20~30 Gy/5~6 fx could be the good treatment option to the patients with metastatic brain tumor. This study suggests that the fractionation schedule for FSRT should be determined in consideration of performance status, number of metastasis, tumor volume, location, presence of extracranial disease, and age.