This study examined the time course effects of conjugated linoleic acid (CLA) on the body weight, adipose depots and lipid profiles of ICR male mice using two different sources of fats in the diet Ninety eight mice weighing 25 to 30 g were divided into four groups: beef tallow (BT) and fish oil (FO), beef tallow with CLA supplementation (BTC), and fish oil with CLA supplementation (FOC) group. Eight to nine mice in each group were fed with the experimental diets for 1, 2 or 4 weeks, respectively. All mice were fed experimental diets containing $12\%$ of total dietary fat (w/w) with or without $0.5\%$ CLA (w/w). CLA supplementation did not affect the body weight The weight of epididymal and visceral fats were significantly lower in BTC compared to those in BT groups during the periods examined (p<0.05), whereas they were significantly lower in FOC than those in FO only at 4 weeks (p<0.05). The levels of triglycerides in the plasma were significantly decreased in the BTC group than in BT group throughout the experimental periods (p<0.05). But, FOC was only effective at 4 weeks as compared to FO. The levels of total cholesterol and HDL-C were significantly increased in the BTC than in BT during the entire period (p<0.05), whereas there were no difference between FO and FOC on the levelsof total cholesterol and HDL-C. The levels of free fatty acids (FFA) were significantly decreased in BTC than in BT at 1 and 4weeks and in FOC only at 4 weeks as compared to FO (p<0.05). Taken these results together, CLA was more effective in the beef tallow diet in lowering the epididymal and visceral fat weights and triglyceride level rather than fish oil diet with CLA. Furthermore, the effect became clearer at 4 weeks than at one week of the experiment