Spatial electrocardiography based on the lead field concept of McFee and Johnston appears to be theoretically more satisfactory than other systems of vectorcardiography. To determine the normal range of planar loop patterns to be expected with this technic and to compare them with those derived by previous methods, a survey of young adult males has been carried out with particular reference to the sagittal plane. The possible relationship between loop orientation and anatomic cardiac position has been investigated and a comparison made of main loop axes and the corresponding electric axes as calculated from scalar tracing areas.