A dc method is described for measuring the magnetoconductivity tensor of an anisotropic crystal when the magnetic field is along a crystallographic symmetry axis. The method is particularly suited for compounds with large anisotropies, for which conventional techniques are not practical. The sample to be measured is a rectangular parallelepiped, each of whose faces is either free or on a highly conducting substrate. The electrodes are arbitrarily located point contacts. Special attention is given to self‐consistency checks for verifying that the conditions required to apply the method are satisfied. A convenient alternative to the usual procedure of separating resistive and Hall voltages by magnetic field reversal is presented.This new procedure is based on a reciprocity theorem in a magnetic field, proved here apparently for the first time.