In 69 patients undergoing coronary artery bypass grafting for complete coronary revascularization, blood flow was measured in 140 grafts with 243 distal anastomoses (3.52 bypasses/patient). Total blood flow in single grafts and double and triple sequential grafts did not differ significantly, although mean distal flow decreased successively with single (85 cc/min), double (51 cc/min), and triple (32 cc/min) sequential grafts. Total myocardial flow did not vary significantly regardless of the number of grafts placed. Flow measurements in patients with double sequential grafts showed > 20% overlay in flow between the two distal anastomoses. The data suggest significant but incomplete collateral supply between adjacent coronary beds consistent with the concept of any individual area of myocardium being a capacitance bed supplied in part by a number of adjacent coronary branches.