The antiobesity effect of commercial kochujang and fermented wheat grains in Sprague-Dawley (SD) rats was studied. The experiment was consisted of 6 groups. Normal, high fat diet (HFD), HFD+raw wheat grains, HFD+first fermented wheat grains (FFWG, with Aspergillus oryzae) HFD+final fermented wheat grains (FiFWG, fermented more for 30~40 days), and HFD+ commercial kochujang. The results showed that final body weight, weight gain, food efficiency ratio, and adipose tissue weight were markedly decreased by the commercial kochujang and the fermented wheat grains, whereas non-fermented raw wheat grains had no such effect. Lipid contents such as total lipid, total triglyceride and total cholesterol decreased in the serum and organs of liver and adipose tissues by the commercial kochujang and the fermented wheat grains as well. These results also indicated that fermented wheat grains exhibited more suppressive effects on high fat induced-obesity than raw wheat grains. Increased fermentation time and adding the red pepper powder resulted in increased the anti-obesity effect. Especially, commercial kochujang showed higher antiobestic effects than fermented wheat grains. These in vivo findings suggested that well-fermented end products of the wheat grains and red pepper powder in kochujang could be useful in the prevention of obesity.