The hypothalamic-pituitary neurosecretory system of rabbits with anaphylactic shock was investigated by morphometric and histochemical methods. The volumes of the perikarya were increased and the dimensions of the nuclei and nuclei of the neurosecretory cells were reduced, and the content of neurosecretory substance throughout the neurosecretory system was increased. In rabbits dying from shock the volumes of the nuclei and nuclei were reduced by a lesser degree, the dimensions of the perikarya were changed, and the content of neurosecretory substance in the posterior lobe of the pituitary was reduced. In animals surviving shock the synthesis of neurohormones by the neurosecretory cells was thus sharply stimulated, but liberation of neurohormones from the posterior lobe was inhibited. In aminals dying from shock hormone formation in the neurosecretory cells was stimulated to a lesser degree, but the processes of liberation of neurohormones from the posterior lobe of the pituitary were probably intensified.