We report a 49-year-old woman with radiation neuropathy, which occurred 7 years after radiation therapy for supraclavicular lymph node metastasis of breast cancer. The patient had noticed a hard induration in the right breast twelve years previously and had a radical operation for right breast cancer. After surgery, she remained well until 7 years ago when she noted a right supraclavicular mass. Based on a diagnosis of metastasis of breast cancer at the right supraclavicular lymph node, she received radiation therapy at 50 Gy in 25 fractions to the lesion. Seven years after radiation therapy, the patient noted muscle weakness of II-V fingers of the right hand, followed by muscle atrophy of the right forearm. We diagnosed her condition as radiation neuropathy based on the absence of a mass lesion in the right supraclavicular region, no RI deposits in that region on Ga and bone scintigraphy, findings supportive of a lesion in the right brachial plexus on EMG and the history of radiation therapy for supraclavicular lymph node metastasis of breast cancer 7 years previously. We treated the patient with pulse therapy with high-dose oral prednisolone. Subsequently, the muscle weakness and atrophy of the right forearm and fingers have improved gradually. We suggest that pulse therapy with high-dose oral prednisolone for radiation neuropathy should be evaluated in a clinical trial, since few therapies are available for this condition.