The goal of the investigation was the determination of the influence of Ca(2+), vitamin B6 methionine, tryptophan, the combination of the listed elements and high-calorie food on the intensity of synthesis and secretion of melatonin. The level of melatonin in the blood serum was being determined through the method of radio-immune (immune-enzyme) analysis. Based on the results received it was found out that the influence of the vitamin B6, tryptophan and their combination in the organism of the tested objects - white rats) resulted in the considerable increase of formation of melatonin. In the conditions of feeding them with high-calorie food - the value of melatonin in blood is sharply reducing. Consequently we may conclude that the vitamin B6 and tryptophan separately and in combination, either directly or through some other mechanism participate actively in biosynthesis and secretion of melatonin. The high-calorie food through unknown mechanism to us reduces the formation of the melatonin in epiphysis. This might point to the important role of the deficit of melatonin in etiopathogenesis of the diseases, detected and developed on the background of hypercholesterinemy.