A cardiovascular epidemiologic study was performed in three different areas in Okayama prefecture in 1980. The relationship between serum total and HDL-cholesterol and blood pressure, ECG findings, clinical disorders, obesity, drinking and smoking was examined in a total of 1092 subjects, with an age-range 49-79 years. The following results were obtained: 1) Along with an elevation of blood pressure, Code 1-0 in the ECG decreased and the code for left ventricular hypertrophy (a combination of two or more subcategories of Code 3 or of Code 3 with Code 4 or 5) increased. Code 4+5 increased in parallel with the systolic blood pressure and Code 5 increased directly with the diastolic blood pressure. 2) In the group of essential hypertension and coronary arterial disorders, HDL cholesterol/total cholesterol ratios were significantly low, and total cholesterol and the Atherogenic Index were in high compared with the normal group. 3) Along with an increase in body weight, the HDL-cholesterol/total cholesterol ratio decreased, while total cholesterol and the Atherogenic Index increased significantly. 4) The group with a drinking habit showed high HDL-cholesterol values but HDLcholesterol showed lower values in the group with a smoking habit.