The study was designed to observe the effects of dietary intake of three different levels of polyunsaturated to saturated fatty acid (P/S) ratio on plasma HDL - cholesterol and triglyceride in plasma and tissues of adult rats. Rats were assigned into the three diet groups, composed of protein 24%, carbohydrate 46%, and fat 30% of total caloric intake. However, the P/S ratio of fat was adjusted by using beef tallow, corn oil and perilla oil to give 0.2, 1.1 and 6.0. All groups were fed ad libitum for 4 week. Plasma cholesterol level was decreased but net significantly with increasing P/S ratio of dietary fat, and showed significant negative correlation coefficient. Plasma TG level was also decreased with increasing PUFA level of dietary fat. However, the effect of P/S ratio (6.0) was not greater than that of P/S ratio (1.1) on plasma TG concentration. This implied that high level of PUFA was not required to change plasma TG level as much in the case of HDL-cholesterol. Plasma HDL-cholesterol was significantly increased only in the group of P/S ratio 6.0 which suggested that high level of dietary PUFA was required to increase HDL level. There was a decreasing trend in the levels of total cholesterol and TG per g liver with increasing P/S ratio of dietary fat. There was no effect in the levels of TG per g skeletal muscle by P/S ratio but the level of cholesterol per unit skeletal muscle was rather increased with increased P/S ratio.