To determine whether vein graft length is a factor that influences infrapopliteal bypass patency, we reviewed 237 consecutive reversed saphenous vein bypasses performed because of critical ischemia during a 5-year period. One hundred seventeen long vein grafts (LVGs) were longer than 40 cm (42 to 92 cm, mean 60.9 +/- 9 cm) and 120 short vein grafts (SVGs) were 40 cm or shorter (6 to 40 cm, mean 24.7 +/- 8 cm). Ninety-three percent of the LVGs originated from or were proximal to the superficial femoral artery (SFA) whereas all of the SVGs originated at or distal to the SFA. The cumulative patency rate for LVGs at 3 years was 45% and for SVGs was 63% (p less than 0.025). In the absence of an intact pedal arch, 3-year patency rates for LVGs (51 cases) and SVGs (78 cases) were 22% and 53%, respectively (p less than 0.01). High intraoperative outflow resistance measurements (greater than 0.7 mm Hg/ml/min) were encountered in 25 cases. Of these, occlusion within 6 months occurred in six of seven cases with LVGs and in only 8 of 18 cases with SVGs (p less than 0.05). Wound complications at vein harvest sites occurred in 17% of LVGs and in only 6% of SVGs (p less than 0.01). Of 16 additional cases in which a proximal patch angioplasty or percutaneous transluminal angioplasty was performed tandem with a short distal vein graft, four occluded (less than 6 months) and 12 remained patent from 3 to 43 months (mean 12.6 months).(ABSTRACT TRUNCATED AT 250 WORDS)