When peripheral arteriosclerosis progresses to the stage where blood flow through both primary and collateral circulations is impaired seriously, arteriolar relaxants, physical therapeutic, pharmacological and surgical, may aggravate the nutritional deficit. Although tissue viability is maintained precariously, limited activity may be tolerated unless the delicate balance between blood supply and metabolic activity is upset by the vicious circle of rest pain and dependent edema. This vicious circle constitutes an immediate threat to the structural integrity of the limb. Rest pain must be controlled if the delicate balance between blood supply and metabolic activity is to be restored and the threat of amputation mitigated. Intravenous injections of procaine may be of value.