Twenty-eight patients who underwent bypass procedure with Gore-Tex grafts for atherosclerosis obliterans of lower extremities, with long-time warfarin therapy, were compared to a group of 9 patients, in whom Gore-Tex grafts were used similary, but without warfarin therapy. Comparison of results revealed the graft patency ratio 89% of the warfarin therapy group to be superior to the ratio of 58% of the non-warfarin group, and the difference is statistically significant. And the twenty grafts of the warfarin group, whose follow-up period that ranged frome 12 to 44 months were compared to the ten grafts of non-warfarin group, whose follow-up period that ranget from 9 to 38 months., Comparison also revealed that the patency ratio of 95% of the twenty grafts to be significantly superior to the 58% of the ten grafts. Judging frome these outcome, we decide to continue to manage the bypassed patient with Gore-Tex grafts on the long-time warfarin therapy to keep the graft patency ratio high.