The research included a study of (50) samples of blood serum healthy control comparedwith (50) samples of atherosclerotic patients. It was found that the normal range of arylesterase activity in control group (117.22±5.03 U/ml), The enzyme activity was not affected by sex and decreased with aging. Also sex and age had no effect on the enzyme activity in patients. A significant decrease in activity, HDL, total protein, albumin and globulin, was found also that a significant increase of total lipids, where as no change was found in total cholesterol, triglyceride, VLDL, LDL and calcium in serum of atherosclerotic patients compared with control group. Correlation coefficient between arylesterase activity and the clinical variables in control and patients groups showed a linear relationship of arylesterase activity with total protein in control group, with HDL and albumin in patients group.