Parameters of platelet aggregation under the influence of different ADP concentrations and vascular endothelial antiaggregation activity using a test of shoulder compression with a sphygmomanometer cuff were investigated in 46 persons aged up to 60 [14 examinees had type IIa hyperlipoproteinemia, (HLP), 10--type IIb, 10--type IV-V HLP, and 10 healthy donors]. CHD was diagnosed in 19 of 34 HLP patients. In 2 examinees CHD was unaccompanied by HLP. A raised amplitude of the aggregation of plates and a decrease in the threshold of their sensitivity to ADP were established in the persons with types IIa and IIb HLP and in CHD without HLP. In the examinees with type IV-V HLP the amplitude of platelet aggregation was lowered significantly, and the threshold of sensitivity to the inductor was raised. Endothelial antiaggregation activity in all types of HLP and in the persons with CHD without HLP was inhibited.