To investigate the effects of angiotensin converting enzyme inhibitor captopril, calcium channel blocher diltiazem and beta- adrenoceptor agonist dobutamine on the permeability of rat cultured aortic endothelial monolayers. Methods: The isolation and culture of rat aortic endothelial cells adopted the method of Chen SF. Rat aortic endothelial cells were seeded on the nitrocellulose microporous filters. 8 d after seeding, the monolayers were used for measuring the permeability by mounting monolayers. Before perfused, Monolayers were treated by captopril, diltiazem and dobutamine for 4 h successively. The prepared filters were mounted on the Boydon chambers and perfused with hyperlipemia containing FITC-labelled albumir. The fluid filtering through the monolayer and filter was collected and the albumin concentration were measured. At the same time Tch, TG, aPA and aPB concentrations of the collected fluid were also measured by ELISA. Results: The above three drugs decreased the permeability of confluent aortic endothelial cells monolayers to water, cholesterol, triglyceride lipoprotein A and lipoprotein B significantly. Dobutamine had more significant effects than two other drugs. Diltiazem, but not two other drugs decreased the clearance of albumin obviously. Conclusion: Captopril, diltiazem and dobutamine may decrease the infiltration of lipids and lipoproteins into the subendothelial space, thus they can be used to prevent and ameliorate atherosclerosis.