An analysis has been made of the three-dimensional branching structure for the basal and apical dendrites of cortical neurons in an adult rabbit. The real branching angles of basal dendrites and apical oblique branches are in the same range, but differ from those of the apical main shaft. Therefore, several different parts of the apical dendrite have to be distinguished on anatomical grounds, coincident with the presynaptic areas distinguished in the literature. The bifurcations of basal dendrites are essentially symmetrical. The mode of outgrowth, however, is non-symmetrical. Redirection of dendrites will, therefore, occur. This redirection is often not complete, so that a large variability of branching angles results. The possible significance of the observed symmetry is discussed.