Significant increase of the elderly in the demographic structure of a modern society is one of the main reasons for increase in the number of patients with diabetes type 2 and impaired glucose tolerance. The purpose of this research was to study impact of Pancragen (tetrapeptide Lys-Glu-Asp-Trp) on endocrine function of the pancreas of non-human primates, female rhesus monkeys, and to elucidate the possibil- ity of its use for correction age-related dysfunction of pancreatic islet apparatus. In old animals after the glucose administration (standard dose) in control period, a reduced glucose "disappearance" rate and a higher values of insulin and C-peptide peaks (5 and 15 min after the glucose injection) were observed in comparison with young animals in similar experiments. Pancragen administration (50 μg/animal per day during 10 days, intramuscularly) to old monkeys caused markedly increased the glucose "disappear- ance" rate, normalized the plasma insulin and C-peptide dynamics in response to glucose administration. The recovering effect of Pancragen on the function of the pancreas partially remained 3 weeks after discontinuation of the drug. Thus, Pancragen is a promising factor for restoring the age-related endocrine dysfunction of primates.