The authors report their experience of coronary artery disobliteration by laser in 10 patients. This was a preliminary study to assess the effects of an Argon laser on atheromatous coronary stenosis in vivo. This technique was used during coronary bypass surgery. Two series of patients were treated: an initial group of 5 patients who underwent laser therapy associated with coronary bypass surgery; a second group undergoing laser therapy alone without distal bypass grafting. The results were assessed by immediate angiography in the first series and by the passage of calibrated probes in both series. Secondary control angiography after 3 weeks was carried out in all patients. The immediate results showed a constant improvement (less than 25%) in the degree of stenosis. However, secondary angiography showed secondary occlusion in 88% of cases. These preliminary results show: the immediate efficacy of Argon laser in reducing the size of atheromatous plaques, the innocuity of the method as there were no postoperative deaths, a high incidence of secondary failure which could be related to the type of indication (competitive flow in the first group and poor distal run off in the second group of patients) or to the type of laser used. The authors consider this to be a promising technique but a lot of clinical and experimental work remains to be done before it can be adopted for routine use.