This study was performed to investigate the effects of ethanolic extract of Ulmus davidiana root (UE) on lipid metabolism in mice fed a high-fat diet (HF) for 7 weeks. Forty male ICR mice were randomly divided into four groups; normal diet group (N), high-fat diet group (HF), HF with 0.5% UE (HF-L) and 1% UE (HF-H) group. Body weight, body weight gain, and liver weight in the HF group was significantly higher than in the N group, while those of the HF-L and HF-H group were unchanged. UE improved HF-induced dyslipidemia by reducing serum triglyceride, total cholesterol, and the atherogenic index. There was no difference in serum HDL-cholesterol among experimental groups. However, the HDL-cholesterol/total cholesterol ratio was significantly increased in the HF-L and HF-H group. Histological analysis showed that HF-fed mice developed hepatocellular microvesicular vacuolation as a result of fat accumulation. These changes were attenuated by 1% UE supplementation. In addition, hepatic triglyceride and cholesterol levels in the HF-H group significantly reduced. Taken together, these results demonstrated that lipid levels in the blood and liver were reduced by UE, suggesting that it might be beneficial for the prevention and treatment of hyperlipidemia and fatty liver.