This study was carried out to evaluate the effect of Cnidi rhizoma (CR) water extract on fat accumulation In fatted rats induced by the oral high fat administration for six weeks. To accomplish this evaluation, the serum and liver tissue have been examined for enzyme activity, cortisol and insulin level. The change of liver or tissue have been observed by the light microscope. GOT GPT and LDH activities were lower than the control group. Insulin and cortisol were higher than the control group, due to the fat accumulation. The liver of the control group observed by the tight microscope appeared to the fatty liver, but CR group showed some improvement of the fatty liver Based on the above results, it was shown that it is possible to improve fat accumulation induced by high fat dietary through using the oral administration of Cnidi rhizoma water extract.