In a series of 20 coronary excimer laser angioplasties, two patients presented with a peculiar type of malignant restenosis 6 and 8 weeks after a successful laser angioplasty procedure. One patient had a successful recanalization of an occluded left anterior descending (LAD) coronary artery and the second patient had a successful angioplasty of a subtotal proximal stenosis of the left anterior descending coronary artery. After the procedure, no ischemia could be demonstrated by exercise ECG and thallium scintigraphy. Both patients were free of angina until the sudden development of nocturnal angina several hours before reangiography, which showed subtotal restenosis in both cases. One patient had a mammaria graft on the LAD and the second patient underwent a successful balloon angioplasty. This uncommon sudden and malignant development of restenosis seems to be related to the excimer laser angioplasty procedure and warrants some caution with the indiscriminative use of this new angioplasty procedure.