Background: The use of sequential anastomoses in coronary artery bypass grafting (CABG) is still controversial. This study aimed to evaluate the mean blood flow (MU ) rate and pulsatility index (PI) of single and sequential saphenous vein grafts to the posterior descending artery (PDA) in the same patient during off-pump CABG (OPCABG). Methods: Sequential saphenous vein grafts were used to bypass the diagonal artery (Diagonal) (side-byside), obtuse marginal artery (OM) (side-by-side) and PDA (end-to-side). The anastomoses of Diagonal and OM were temporarily occluded with bulldog clamps, making the sequential graft a "single" graft to PDA. The MBF and PI of this "single" graft to PDA were measured with transit-time flow measurement (1"1 FM). Then the bulldog clamps were removed and the MBF and PI of sequential graft to PDA were measured again and compared to those of the "single" graft in the same patient. Anastomoses were evaluated with coronary CT angiogram at 6 months. Results: A total of 128 patients with triple vessel disease were enrolled (96 men; mean age, 66.0 +/- 8.0 years; range, 54-80 years). The MBF of the "single" vs. sequential graft to PDA was 20.6 +/- 9.1 vs. 21.4 +/- 10.1 mL/min (P=0.472). The PI of 'single graft' vs. sequential graft to PDA was 1.7 +/- 0.6 vs. 1.7 +/- 0.5 (P=0.941). The patency of all grafts was good in all patients after 6 months of follow-up. Conclusions: There were no hydrodynamic differences between single and sequential grafts to PDA in OPCABG.