Four cases of subclavian artery occlusion occurring 5-17 years after irradiation for breast carcinoma are presented. Although arterial insufficiency is a rarely reported sequel to radiotherapy, it may be the cause of pain and disability in the upper extremity in a postmastectomy patient. Particular attention should be paid to the presence of a bruit over the subclavian and axillary arteries. Arteriography will often reveal a short, segmental lesion of the subclavian artery that frequently can be repaired surgically.