Operative technique and results of angioplasty of the left main coronary artery (LMCA) for isolated LMCA disease are reported. Nine consecutive patients, six men and three women, were operated upon. Their ages varied from 46 to 69 years, mean 51 years. All had 50% to 90% stenosis of the LMCA and Class III angina. Cardiopulmonary bypass and a cold cardioplegic solution were used for all operations. There were no operative deaths or infarctions. Follow-up ranged from 0.5 to 4 years, mean 1.9 years. Except for the first patient, who has new stenosis of the proximal anterior descending artery, all patients are free of angina. Repeat angiography in five patients showed a widely patent LMCA with excellent runoff. Our preliminary results suggest that angioplasty of the LMCA can be carried out with low operative risks. The technique appears to be a promising alternative to coronary artery bypass grafting in isolated LMCA disease.