The regular injection of hormone results in a decrease of phosphate groups content in total and non-histone proteins of rat liver chromatin. The quanitity of organic phosphate in total liver histone was increased by 17 per cent. This result is due to the increase of the alkaline-labile phosphate content in lysine-rich histones (approximately by 25 per cent) and unsignificant decrease in arginine-rich histones (approximately by 5 per cent). The intensity of the 32P incorporation was increased under the effect of somatotropin in all fraction of basic proteins; this increase being especially for lisine-rich histone subfractions. The quantity of histone f1 subfractions was also increased. A possible importance of changes in the degree of chromatin protein phsophorylation for realization of growth hormone function on the transcription level is considered.