This study was conducted to determine the effects of chromium-methionine (CrMet) supplementation at various levels on obesity index, body fat, and serum glucose, insulin and leptin in rats. Forty male Sprague-Dawley rats were randomly assigned to one of four dietary groups and fed AIN-76 semi-purified basal diets supplemented with 0, 300, 600 or 1200 ppb Cr from CrMet. After 4 weeks on the respective diets, the rats were killed and serum glucose, insulin and leptin concentrations were determined. The CrMet supplementation did not affect weight gain, feed intake or feed efficiency ratio, fasting glucose, insulin or leptin levels among treatment groups. Although final body weight in all treatments were not significantly different, naso-anal length was longer in the 1200 ppb CrMet group than those of control or other groups (p<0.05). The lowest obesity index and body fat were observed in the 1200 ppb dietary group (p<0.05). The obesity index of the rats fed 1200 ppb supplemental CrMet was lower than in the other groups. These results suggest that CrMet supplementation results in a significant decrease in obesity index, possibly by decreasing the body fat that corresponded to increasing CrMet dosage.