Background: Transmyocardial laser revascularization has emerged as an alternate treatment of angina refractory to conventional methods. The aim of this experiment was to study the hemodynamical effects of progressive laser drilling of the left ventricle in the calf. Methods: Channels were drilled through the entire thickness of the left ventricular free wall in the transmural group (6 animals), and through its outer two-thirds in the non-transmural group (6 animals). Channels were performed either until hemodynamical collapse or until there was no room left for further holes. Results: Both groups showed a progressive increase of the heart rate and the pulmonary pressures, a progressive decrease of the cardiac output, while the right atrial pressure and the mean arterial pressure did not vary significantly. Except for the heart rate, these variations were not dramatic. The animals of the transmural group died of ventricular fibrillation after 160 till 290 holes, while those of the nontransmural group had the whole surface of the left ventricle drilled with 470 till 510 channels without collapse. The procedure time were 99 ± 14 min and 219 ± 4 min respectively. Conclusions: The proportion of the left ventricle injured by the laser beam and the duration of the procedures especially in the non-transmural group show that the cardio-vascular system of the calf can withstand an extended myocardial lesion over a prolonged period.