While annual attrition and high break-down rate of saphenous vein graft (SVG) used for CABG has widely noted in Western countries, no sizable studies have yet available in Japan. We studied 142 SVGs of 77 pts, which we divided into two groups; 80 SVGs of 44 pts in mid-term period (5 to 8 years after surgery) and 62 SVGs of 33 pts in long-term period (9 to 17 years after surgery). The patency rate of SVGs was 69% in mid-term and 77% in long-term. Whereas these patency rates at each periods were superior to those reported from USA and European countries, a quarter of SVGs in mid-term period and a half in long-term period had significant stenotic changes (over 50%). Of patent SVGs, diseased SVGs reached 36% in mid-term period and 73% in long-term period. In conclusion, although the patency rate of SVGs in Japanese patients was higher than that of the Western countries, vein graft disease apparently occurred in a large proportion of patent SVGs.