Abstract： Objective　Laser-induced myocardial injury was investigated in a canine transmyocardial laser revascularization model.Methods　A total of 23 channels were created in the left ventricles of 5 animals with a CO2 laser. Four animals were sacrificed immediately and one at week 2. Lactate dehydrogenase and succinate dehydrogenase in channel regions were examined with a Nitro-BT method staining.Results　Immediately after the procedure, laser channels and surrounding injured myocardium could be stratified from the center to the border into 5 concentric zones, i.e., vaporized zone, carbonized zone, enzyme-disappeared zone, enzyme-decreased zone and enzyme-concentrated zone. Two weeks later, the phenomenon disappeared.Conclusions　Immediately after transmyocardial revascularization, there is a ring of enzyme-concentrated zone at the outermost region of injured myocardium. Two weeks later, enzyme activities of reversibly injured myocytes appear to have recovered.