Systolic occlusion leg and brachial pressures were determined using a Doppler ultrasonic method in 24 diabetic subjects with either past or evolving gangrene due to arterial occlusive disease of the lower extremities. The leg-brachial ratios were correlated with x-ray determined leg vascular calcification. Ratios above 1.10 were invariably associated with heavy continuous calcification of the tibial vessels; lesser degrees of arterial calcification had normal or depressed leg-brachial ratios. Medial calcification might be causally related to the abnormally elevated leg systolic pressures not infrequently noted in diabetic patients. Based on the observed occurrence of reamputation in association with normal or elevated leg-brachial ratios, it appears that a Doppler pressure index above 0.90 is not a reliable indicator of adequate blood flow in severe diabetic occlusive arterial disease.