Fat saturation degree and the age of bird are two important factors for broilers’ ability to digest fats. It has been shown that hepatic fatty acid synthetase activity is decreased by diets with added sunflower oil (rich in PUFA of n-6 series) compared with those fed lard and this can result in abdominal fat pad reduction. (Sanz et al., 2000). It is well known that dietary intake of n-6 and n-3 PUFAs is effective in lowering blood lipid level, but they differ in their effect on serum lipid concentrations. It has been observed that n-6 fatty acids lower serum cholesterol level, but not triacylglycerol; n-3 fatty acids lower both serum cholesterol and serum triacylglycerol level in experimental animals (Berr et al., 1993). The objective of this study was to survey the effects of different dietary unsaturated to saturated fatty acids ratio on performance, abdominal fat pad and serum lipids in broiler chickens.