A total of 114 consecutive patients undergoing extracorporeal shock-wave lithotripsy had serial creatinine kinase (CK) with isoenzymes and serial electrocardiograms (ECG). There were significant changes in both heart rate and CK post-lithotripsy. However, this did not appear to be due to elevation of the myocardial component of CK. While there were some random ECG changes pre- and post-lithotripsy, none appeared to be directly related to the procedure.