In order to study effect of plasma lipids on ATPases activities in erythrocyte membrane, contents of plasma TC, LDL-C and HDL-C and activities of Na⁺-K⁺- and Ca²⁺-Mg²⁺-ATPase were determined in 28 hypercholesterolemia patients and 16 control.The Na⁺-K⁺- and Ca²⁺-Mg²⁺-ATPase activities were reduced in these patients. Negative correlations were shown between two ATPase activities and plasma TC and LDL-C levels, but positive correlation was shown between Na⁺-K⁺-ATPase activity and plasma HDL-C level in all groups. These studies may be important for probing into mechanism of atherosclerosis formation and prevention and cure of this disease. This problem is discussed in the paper.