Objective To investigate the clinical applicant value of color Doppler flow imaging(CDFI)on evaluating the brachial artery endothelial function. Methods 30 patients with primary hypercholesterolemia(PHC) administered with simvastatin(SVT)for 8 weeks.The changes of brachial artery intemal diameter under the reactive hyperaemia situation or after taking nitroglycerin were evaluated by CDFI before and after treated with SVT respectively. Results The changes of brachial artery diameter before administered with SVT in PHC patients in reactive hyperaemia condition were 3 38±5 48%.There was a statistically significant difference between experiment group and control group(17 58±6 47%)( P 0 001).The changes of brachial artery diameter after treatment with SVT in reactive hyperaemia condition were 14 68±5 05%.There also was a statistically significant difference between before and after treated with SVT( P 0 001). Conclusion It is a simple,accurate and effective method to evaluate the brachial artery endothelial function with color Doppler ultrasound. [