Aim To investigate the effects of transmyocardial laser revascularization (TMLR) on acute myocardial ischemic injuries. Methods Nd: YAG laser with a guartz optical fiber was treated to irradiate the canine acute myocardial ischemic area and the dynamic changes of epicardial ST-segment electrocardiograms serum creatine kinase level were measured following TMLR. Results The deviant summation of ST segment (∑ST) in single channel group was 42.3±12.8 mm, the total numder of extraordinary elevation point in ST segment(NST) was 6.5±1.3 and ∑ST in the multi-channel group was 20.1±6.72 mm, NST 5.3±0.6. Both were significantly lower than ∑ST 80.4±24.2 mm, NST 9.8±1.1 before being laser-treated respectively (P<0.05 orP<0.01). As being compared to the peak valve of contrast group in the corresponding period, ∑ST and NST in laser single channel group and multi-channel group were significantly lower than those in the contrast group(P<0.05). There was no significant difference(P>0.05) in serum activity CK level in all groups. Conclusion Transmyocardial laser revascularization (TMLR) can reduce the injuries of ischemic myocardium when canine coronary artery is ligated.