Coronary disease in cardiac transplant patients is a major factor in the limitation of long term survival. The aim of this study was to compare the results of angioscopy with those of coronary angiography performed systematically every 18 months in our center. Twenty-nine patients (31 angioscopies) were assessed 38 +/- 21 months after transplantation. The appearance observed by angioscopy were: 1) normal, 2) yellow pigmentation of the arterial surface, 3) elevated plaque < 50%, 4) elevated plaque > or = 50% stenosis. Angiography was: 1) normal, 2) iregularities of the lumen or < 50% stenosis, 3) > or = 50% stenosis. The films were viewed by two independent investigators. Angioscopy was performed on the left anterior descending artery (N = 35), the left circumflex (N = 24) and the right coronary artery (N = 9). One to three arterial segments were examined per vessel (total of 117 segments: average 3.8 segments per patient). Angioscopy was uniterpretable in 13/117 (11%) of cases. Of the 81 (78%) segments considered normal at coronary angiography, only 55 seemed normal at angioscopy (68%). Of the 23 segments considered to be abnormal at coronary angiography, all were also considered to be abnormal at angioscopy. The authors conclude that coronary angioscopy seems to be more sensitive than coronary angiography for the detection of coronary disease due to chronic rejection. Prospective studies are required to determine whether the infra-angiographic angioscopic lesions correspond to earlier stages of coronary disease of the cardiac graft.