The purpose of this study was to determine whether a clampless facilitating device (CFD) to perform proximal aortocoronary anastomoses would result in a lower incidence of cerebral embolic events compared with a partial clamping strategy during off-pump coronary artery bypass (OPCAB). After epiaortic ultrasound confirmed the mild aortic disease (Grades I and II), 57 patients were randomly assigned to have proximal anastomoses using a partial-occluding clamp (CL, n = 28) or a CFD [Heartstring (HS), n = 29] (Maquet Cardiovascular LLC, San Jose, CA). Solid and gaseous emboli in the middle cerebral arteries were detected using transcranial Doppler ultrasonography. The mean number of proximal anastomoses was similar between groups 1.93 ± 0.72 (CL) and 1.72 ± 0.70 (HS) (P = 0.28). The mean number of gaseous plus solid emboli was greater in the CL group than the HS group (90.0 ± 64.0 vs. 50.8 ± 36.6, P = 0.01). Emboli were fewest in patients undergoing HS anastomoses using the suction device. The number of intraoperative cerebral emboli was proportional to the number of proximal anastomoses in the HS groups, but independent of the number of proximal anastomoses in the CL groups. Among patients with a low burden of aortic atherosclerosis, partial clamping of the ascending aorta during OPCAB was associated with more cerebral embolic events compared with an anastomosis with a CFD.