Over the last 25 years, the cardiovascular effects of marine omega (0)-3 fatty acids (also referred to as n-3 fatty acids) have been the subject of increasing investigations. In the late 1970's epidemiological studies revealed that the Greenland Inuits had markedly reduced rates of acute myocardial infarction compared with Western controls. These observations spawned hundreds of subsequent studies, beginning with the initial epidemiological observations and then moving to cell culture, animal and clinical studies, all of which confirm the cardioprotective effects of n-3 fatty acids. This investigation was therefore, iniated in order to clarify the effects of king fish oil on the concentration of lipids, nonesterified fatty acid and total antioxidant status in the serum of experimentally-induced hypercholesterolemic rats. Wister rats were randomly divided into five groups: control group (Group A), group B, C and D were fed high cholesterol (HC) diet (2%) for 4 weeks followed by another 4 weeks of HC diet, normal diet and fish oil (FO) (5%) diet, respectively. In group E the rats were co-fed with HC plus FO diet for 8 weeks. As expected serum total cholesterol in rat increased significantly (P< 0.05) following feeding of high cholesterol diet (118+2 mg/dl) in comparison with group A (59.2=7.6 mg/dl). This increase was due to raised very low density lipoprotein (VLDL-) and low density lipoprotein (LDL-) cholesterol. Dietary fish oil significantly decreased the serum total cholesterol by 63%, triglycerides by 43% and nonesterified fatty acids by 65% with concomitant increases of total antioxidant status (95%) and high density lipoprotein (HDL-) cholesterol (26%). In group E, FO diet seems to prevent any increase in serum total cholesterol and NEFA levels compared to Group B level, but the fish oil diet did significantly decrease the triglycerides level (P<0.05) in comparison with Group B. The mixed diet of FO and HC did increase significantly (P<0.05) the level of serum HDL-C and TAS in comparison with group B. In conclusion, this study suggests that king fish oil could act as an important component in the dietary management of atherogenic serum lipids and antioxidative status.