Objectives : The purpose of this study is to investigate the effects of hot pepper extract and capsaicin on the adipogenesis in 3T3-L1 cells, lipolysis in rat epididymal adipocytes and histological changes in porcine adipose tissue. Methods : Inhibiton of preadipocyte differentiation and/or stimulation of lipolysis play important roles in reducing obesity. 3T3-L1 preadipocytes were differentiated with adipogenic reagents by incubating for 3 days in the absence or presence of hot pepper extract or capsaicin ranging from 0.01 to $1mg/m{ell}$. The effects of hot pepper extract and capsaicin on adipogenesis were examined by measuring GPDH activity and by Oil Red O staining. Mature adipocytes from rat epididymal fat pad was incubated with hot pepper extract or capsaicin ranging from 0.01 to $1mg/m{ell}$ for 3 hrs. The effects of hot pepper extract and capsaicin on lipolysis were examined by measuring free glycerol released. Fat tissue from pig skin was injected with hot pepper extract or capsaicinCFP ranging from 0.1 to $10mg/m{ell}$ to examine the effects of hot pepper extract and capsaicin on histological changes under light microscopy. Results : The following results were obtained from present study on adipogenesis of preadipocytes, lipolysis of adipocytes and histological changes in fat tissue. 1. Hot pepper extract and capsaicin inhibited adipogenic differentiation at the concentration of 0.1 and $0.01mg/m{ell}$, respectively, indicating that capsaicin was more effective in inhibiting adipogenesis than hot pepper extract. 2. Hot pepper extract and capsaicin decreased the activity of glycerol-3-phosphate dehydrogenase(GPDH) at the concentration of 0.1 and $0.01mg/m{ell}$, respectively, indicating that capsaicin was more effective in inhibiting adipogenic differentiation than hot pepper extract. 3. Hot pepper extract and capsaicin increased glycerol release at the concentration of $0.1mg/m{ell}$. There was no difference in lipolytic activity between hot pepper extract and capsaicin at the corresponding concentration. 4. Hot pepper extract and capsaicin caused shrinkage of fat cells, resulting in cell death at the concentration of $1.0mg/m{ell}$, although capsaicin exerted this action over wide area than hot pepper extract. Conclusions : These results suggest that hot pepper extract and capsaicin efficiently inhibited adipogenesis, increased lipolysis of adipocytes and caused to shrink fat cells. Future studies are needed to make use of hot pepper extract pharmacopuncture for the treatment of obesity.