Background: This study was undertaken to evaluate the use of Transit time flowmetry (TTFM) to identify the malfunctioning graft for the need of graft revision or intervention while performing Off-pump coronary artery bypass grafting (OPCAB). Methods: From July 2014-July 2018 transit time flowmetry was performed on 1206 grafts in 424 patients who underwent OPCAB. The grafts were taken as patent and acceptable if the mean graft flow was more than 20 ml/minute, Pulsatility index (PI) of < 5 and Diastolic flow (DF) more than 50% with a minimal systolic spike. The grafts which did not fulfill the above criteria were revised/appropriate intervention done after identifying the cause for graft malfunction. Results: A total of 1203 grafts were measured in 424 patients who underwent OPCAB. Out of 1203 grafts measured, 51 grafts in fours nine patients showed abnormal flowmetry reading requiring graft revision or intervention. The cause for graft malfunction was graft twisting, anastomosis stenosis, graft kinking, Lima spasm, coronary dissection, reversed vein, graft anastomosis thrombosis and retained coronary shunt. All fifty-one grafts flow returned to normal after graft revision or intervention. We had one-mortality out of forty-nine patients who had grafts revised and the mortality was not attributed to graft malfunction. Conclusion: Intraoperative evaluation of the graft flow with TTFM promptly helps in identifying the abnormal grafts before the patient becomes hemodynamically unstable. Correcting the abnormal grafts prior to chest closure leads to a reduction in mortality and morbidity which will help in improving the patient’s outcome.