Summary Vectorcardiograms were obtained from 50 young domestic pigs using the Nelson lead system. Compensation for body size and shape is achieved and the resultant dipole moment magnitude reflects heart size. A strong relationship was found between heart size and maximum magnitude. Dipole moment magnitude increased as four pigs increased from five to ten weeks of age. The dipole moment during QRS is considered in light of known pig heart excitation pattern. Dipole locations during QRS, calculated by computer solution of the Gabor-Nelson equations, were in agreement with heart location and excitation data.