Within the past few years, transmyocardial laser revascularization (TMR) has attracted the attention of cardiologists and cardiac surgeons as a therapy for patients suffering from otherwise treatable coronary artery disease. Clinical studies have consistently shown symptomatic improvement that lasts at least 1 year in a majority of patients. The original hypothesis that prompted development of the technique was that direct myocardial perfusion from the chamber could be achieved through chronically patent channels, as is the case in reptilian hearts. Results of our early studies failed to support this hypothesis and we turned to investigations aimed at testing other possible explanations. The experiments, which are reviewed in this article, showed that TMR enhances vascular growth in ischemic myocardium.