To study the effects of high dietary fat and cholesterol on NO synthesis of artery endothelium, 20 male pure New Zealand rabbits were assigned randomly to receive normal diet or high fat and cholesterol diet for 8weeks. Results: severe damage of aortic endothelial cells and atherosclerotic lesions were observed in the study group. Conpared with the control group, the activity of endothelial NO synthetase, its mRNA expression and serum level of NO products decreased, while plasma endothelin in creased in study group. It indicated that high dietary fat and cholesterol could impair artery endothelium and inhibit its nitric oxide synthesis in rabbits. Author's address Li Yong, Shanghai Medical University, Shanghai 200040 PRC.