From April 1981 to June 1987, 57 patients underwent venous coronary bypass graft percutaneous angioplasty and had a minimal follow-up of 18 months. The procedure was elective for 28 patients, urgent for 19, and was considered as an emergency for 10. A total of 64 grafts were dilated that had been bypassed 58 +/- 48 months previously (range 2 to 184 months); lesions were located on the aortic anastomosis in 12 grafts, on the body in 38, and on the coronary anastomosis in 14. Technical success was 95.3% (61 of 64) per lesion; clinical success was 84.4% (54 of 64) per lesion and 82.5% (47 of 57) per patient. Thrombotic complications with images of a lacunar defect occurred in 11 grafts (17.2%). Predictive factors for these complications were: age of grafts 38.5% for greater than 60 month grafts versus 2.6% for less than 60 month grafts (p less than 0.01); site of lesion, body lesion 28.9% versus anastomosis none (p less than 0.01); type of lesion, concentric and short 6% versus other 29% (p less than 0.05); and recent fibrinolysis in 66% versus 10.6% (p less than 0.05). Long-term follow-up is available in the 47 successful patients and the three limited non-Q wave myocardial infarction patients. Two patients died at 13 and 17 months. Long-term angiographic follow-up is available in 45 of 48 patients or 94%. At the end of the study, 35 of 57 (61.4%) venous bypass grafts in 32 patients (64%) were patent after one or more percutaneous transluminal angioplasties.(ABSTRACT TRUNCATED AT 250 WORDS)