Despite advances in coronary artery surgery, technical abnormalities remain a significant cause of early graft closure. The development of small fiberoptic angioscopes now allows direct intravascular magnified examination. Seventy-five distal anastomoses and vein grafts, and five selected coronary arteries were examined with 0.8- to 2.5-mm diameter angioscopes introduced through the proximal vein graft while irrigating with clear cardioplegia. Angioscopic findings were correlated with angiographic data, vessel morphology, graft flow, and postoperative course. Satisfactory images were obtained in 72 of 75 anastomotic inspections. Each examination took less than 2 minutes and required less than 100 cc of flush. Angioscopic abnormalities that did not require revision were noted in 17 of 72 anastomoses; intimal flaps in 9, thrombus on posterior wall plaque in 4, intimal irregularities in 4, bucking of posterior wall in 3, and valve near anastomoses in 1. No outflow obstruction nor misplaced sutures were noted. Average flow rate through the grafts with anastomotic angioscopic abnormalities was 33 cc/min versus 40 cc/min in the remaining grafts. However, regression analysis revealed that low-graft flow was correlated with vessel size and runoff but was not with angioscopic findings. Intracoronary angioscopy revealed discrepancy with angiographic findings in 4 of the 5 examinations. No complications occurred as a result of angioscopy. No graft closure has occurred during early follow-up. Intraoperative angioscopy can be done with minimal alteration of the usual routine. The 24% occurrence of minor angioscopic abnormalities did not appear to compromise graft flow or early patency.