It is unknown to what degree electrical injury causes cardiac muscle damage. We used standard clinical methods and varying combinations of 201Tl scintigraphy (TI), 123I-metaiodobenzylguanidine scintigraphy, echocardiography, 99mTc-RBC angiography, and coronary catheterization to evaluate five patients with high-tension electrical injuries for cardiac damage. The first follow-up examination was performed within 2 months of injury, and the second follow-up was performed more than 6 months after the first follow-up. Electrocardiographic abnormalities were observed in two patients in the acute stage, but no abnormality was detected in the follow-up period. Myocardial perfusion abnormalities were found in all cases with Tl. The degree of injury indicated by Tl was more severe than that indicated by 123I-metaiodobenzylguanidine scintigraphy. Moreover, Tl showed progression of injury in all cases. These preliminary findings must now be confirmed and verified in a larger group of patients.