A 54-year-old-man on hemodialysis was admitted to the hospital because of effort angina. A coronary angiography revealed multiple stenoses including 90% stenosis in the left main trunk. Coronary artery bypass grafting (CABG) was performed with Y-composite grafts constructed by the right internal thoracic artery (RITA) and the free gastroepiploic artery (GEA) which were anastomosed to left anterior descending artery (LAD) and the diagonal branch (D1) using the off-pump technique. After completion of anastomosis, Photo Dynamic Eye (PDE) system showed fluorescence not in the free GEA but at the anastomotic site of GEA to D1. Because the graft spasm of GEA was diagnosed by PDE, papaverine solution was sprayed to the graft, which resolved the spasm and re-anastomosis was avoided. PDE system is a useful tool for the diagnosis of graft spasm, and may contribute to improvement of quality of CABG.