Abstract: The effects of 4 week treatment with tetrandrine（200mg3／d,po） and nimodipine（40mg3／d,po）on renal blood flow（RBF）and glomerular filtration rate（GFR）were studied in 30 patients with essential hypertension,in single blind,random and cross-over trial.The results showed that both of them had a similar hypotensive effect（P＜0.01）,and tetrandrine caused distinct rise in RBF（P＜0.05）,whereas nimodipine tend to rise in RBF but not significantly（P＞0.05）.Both drugs caused comparable effective lowering of renal vascular resistance （RVR，P＜0.01）,while GFR and filtration fraction （FF）remained unchanged（P＞0.05）.No correlation between the effects of tetrandrine or nimodipine on systemic and renal hemodynamic was found.There was no significant difference between the effects of the two drugs on the blood pressure and renal hemodynamics（P＞0.05）.These findings suggested that tetrandrine and nimodipine may improve the renal circulation via intrarenal vasodilator mechanism,and the efficacy of tetrandrine being superior to that of nimodipine.