Blood flow was measured with the electromagnetic flowmeter in the saphenous artery bed (cutaneous) and in the distal femoral and popliteal beds (muscle). The effects of ischemia and of intra-arterial injection with methacholine, l-epinephrine and l-norepinephrine were studied before and again after each injection of progressively increased doses of antiadrenergic drugs. These studies indicate a fundamental difference between the reactivity of cutaneous and muscular vascular beds.