Vectorcardiograms were recorded with the Frank lead system during laparoscopy. Pneumoperitoneum produced the following significant vectorcardiographic changes: (1) The maximum spatial QRS vector increased in magnitude and shifted horizontally and slightly anteriorly. (2) The L/W ratio of the frontal QRS loop decreased. (3) The scalar data of each X, Y, Z lead of the QRS loop increased. In particular, the increases in R of all three leads and in S of lead Z were significant. These results suggest that the changes in the cardiac anatomic position due to lift of the diaphragma and a decrease of left ventricular end-diastolic volume might produce these vectorcardiographic changes during laparoscopy.