5 weeks development of streptozoticin-induced diabetes mellitus in the rats is accompanied with the increase of gastrin-releasing peptide (GRP) immunopositive neurons amount in parvocellular neurosecretory subdivisions of immunopositive fibers increased in these structures:the content of GRP increased in median eminence as well. In supraoptic nucleus and posterior magnocellular subdivision of paraventricular nucleus the amount of GRP-immunopositive neurons increased by the second week of diabetes development with its decrease by the fifth week. Thus, the increase of GRP synthesis in hypothalamic neurosecretory structures in diabetes mellitus may be considered as a compensatory reaction directed on the activation of the central mechanisms of feeding restriction and stimulation of insulin synthesis in the pancreas.