This paper describes the effects of thermally oxidized tallow on the serum lipids profile and radical scavenging activity (RSA) of the lipids extracted from the different tissues of the rabbits. Tallow was thermally oxidized at $130^{circ}C$ for 9, 18, 27, 36 and 45 h respectively. Thermally oxidized tallow was fed to the local strain of Himalayan rabbits for one week. Results show that oxidation increases the formation of hydroperoxides and decrease the level of radical scavenging activity of the tallow. The rabbit serum lipids profile showed a dose dependent increase in triglyceride, total cholesterol and LDL-cholesterol. However, no statistically significant increase was observed in the HDL-cholesterol with an increase of oxidation time. Serum glucose and rabbits body weight decrease significantly (p < 0.05) and was highly correlated with the serum lipids profile. The percent RSA of the lipids extracted from the liver, brain and muscles tissues showed a significant decrease with respect to 0.5, 1.0 and 1.5 g/body weight as well as oxidation time. Data suggests that thermal oxidation and use of thermally oxidized beef tallow is harmful and therefore an alternative way of cooking should be used.