Left main stem coronary stenosis is now uniformly treated with coronary artery bypass grafting. The advent of percutaneous transluminal coronary angioplasty has permitted a non-operative improvement in myocardial blood flow in many cases of single- and multi-vessel coronary atherosclerosis. The use of percutaneous transluminal coronary angioplasty in left main stem coronary stenosis has been sporadic and controversial. Twenty percutaneous transluminal coronary angioplasties were attempted in 19 patients as the treatment of choice for left main stem coronary stenosis in the past 66 months. The primary success rate was 95% (19/20 patients). The emergency surgery was performed only once (5%), and no death occurred secondary to percutaneous transluminal coronary angioplasty itself. In the follow-up (mean 41 months) period, 12 patients (63%) remained in satisfactory condition with no further need for surgical intervention. Seven patients (37%) ultimately required coronary artery bypass grafting. Although coronary artery bypass grafting will remain the fundamental treatment for left main stem coronary stenosis, this series delineates those anatomic and clinical exceptions wherein percutaneous transluminal coronary angioplasty may be utilized as the primary therapy for left main stem coronary stenosis.