This study was attempted to examine the effect of Sopung-Tang(SPT) on the arterial blood pressure in rats and to elucidate its mechanism of action. SPT given into a femoral vein produced a dose-related vasopressor responses followed by vasodepressor responses. SPT-induced hypotension was significantly inhibited by pretreatment with atropine or propranolol while was not affected by chlorisondamine, Prazosin and cyproheptadine. SPT-evoked hypertensive activity was markedly blocked by pretreatment with prazosin but was not influenced by atropine, chlorisondamine, propranolol and cyproheptadine. Infusion of SPT(15.0 mg/kg/30min) did not affect norepinephrine-induced pressor responses. These experimental results suggest that SPT causes biphasically initial hypertensive activity followed by hypotensive activity, and that this hypertension may be due to the stimulation of peripheral adrenergic alpha-receptors and hypotension may be elicited through stimulation of peripheral cholinergic muscarinic receptors and adrenergic beta-receptors.