The present study was undertaken to examine the lipid spectrum of erythrocytic membranes and serum in children and adolescents with type 1 diabetes mellitus (DM-1) during pathogenetic therapy in relation to the duration of the disease, its severity, and the presence of vascular events. Ninety-nine patients with DM-1 and 40 healthy children of the same age were examined. The patients were on basic bolus insulin therapy. In children, DM-1 was ascertained to be accompanied by not only atherogenic serum lipid metabolic disturbances (the elevated levels of total cholesterol, triglycerides, low- and very low-density lipoprotein cholesterol), but also by the impaired lipid spectrum of erythrocytic membranes (reductions in the level of total lipids and the fraction of phosphatidylcholine (PC) with an increase in the level of fractions of tysophosphatidylcholine and phosphaUdylinositol; elevated levels of saturated fatty acids and decreased levels of unsaturated fatty acids in the fractions of PC and phosphatidylethanolamlne; the enhanced microviscosity of deep membranous layers and the modified outer membranous ones). Complex basic therapy resulted in incomplete normalization of the study parameters of the lipid spectrum of serum and erythrocytic membranes in DM complicated by microangiopathies, which requires optimization of conventional therapeutic regimens.