Initial multicenter clinical experience with percutaneous coronary excimer laser-assisted angioplasty is described for 158 lesions in 141 patients. Using a xenon chloride (308 nm) excimer laser generator and 1.5 to 1.75 mm catheters, excimer laser angioplasty was attempted at 135 ns pulse width, 25 to 40 Hz repetition rate, 2 to 5 s laser delivery time and 30 to 60 mJ/mm2 energy fluence. Laser success (greater than 20% improvement in luminal diameter) was achieved in 138 (87%) of 158 lesions, with a reduction to less than 50% stenosis noted in 77 lesions (49%). Overall, laser-assisted balloon angioplasty success (less than 50% residual stenosis without major complication) was observed in 129 (91%) of 141 patients. Procedural complications (abrupt closure 1.3%, side branch occlusion 1.9%, intimal dissection 6.3%, embolization 1.3%, filling defect 1.3%, perforation 1.9% and spasm 1.3% and major complications (non-Q wave myocardial infarction 4.8%, emergency coronary bypass surgery 3.5% and death 0%) were infrequent and predominantly related to subsequent balloon angioplasty. In the early follow-up period (range 1 to 10 months, mean 7), 111 (79%) of the 141 patients remain asymptomatic, whereas symptoms have recurred in 27 (19%) and 3 patients (2.1%) have died. Thus, percutaneous coronary excimer laser angioplasty appears to be a feasible and safe procedure. Assessment of the impact of this technology on the acute complications of and restenosis rates after angioplasty awaits further follow-up analysis.