Experiments on rats (single-action, six-days' hyperepinephrinemia and monoiodacetatic acid intoxication) were performed to study the calcium concentration, alkaline phosphatase and gamma-glutamyltransferase activities in serum at Monckeberg's medial calcific sclerosis modelment. It is established reduction serum level of calcium in an hour past single-acting hyperepinephrinemia, increase it's level after six-days'-monoiodacetatic intoxication, increase of "serum alkaline phosphatase activity/gamma-glutamyltransferase activity" (as indirect evidences the bone isozyme of alkaline phosphatase and parathyroid hormone activity increase) after six-days' hyperepinephrinemia and monoiodacetatic acid intoxication. Probably, these changes in serum calcium metabolism and system it's regulation may play pathogenetic role in early period Mönckeberg's arteriosclerosogenesis.