Thirty-three stenotic lesions were found in 30 vein grafts (17 femoral-popliteal, 13 femoral-tibial) 3 months to 8 years postoperatively--77% appeared within 1 year of surgery. Seventeen (57%) of the patients presented with normal distal pulses, and a similar number were asymptomatic. Only eight (26%) presented with unequivocal clinical evidence of graft stenosis based on decreased pulses and return of ischemic symptoms. Forty percent were completely asymptomatic with normal distal pulses. The mean postoperative ankle systolic pressure index (ASPI) was 0.83 +%- 0.03 (SEM); it fell to 0.57 +/- 0.04 (SEM) when stenosis developed. The peripheral vascular laboratory measurements were the key factor influencing the decision for repeat arteriography in many of these patients and reinforced the need for a repeat arteriogram when the clinical diagnosis was unclear. Early diagnosis of vein graft lesions prior to graft occlusions allowed 24 of 30 of these stenotic grafts to be treated primarily by percutaneous transluminal angioplasty (PTA); 80% remained patent 24 months after PTA. Since most vein graft stenoses can be treated by such a simple, nonoperative technique (PTA), every effort should be made to diagnose and treat lesions prior to graft occlusion. Our experience indicates that frequent vascular laboratory measurements of ASPI are more sensitive then clinical examinations in detecting early vein graft stenosis.