The effect of taurine in anterior hypothalamic area (AHA) on blood pressure was investigated by means of microinjection and spectrophotofluorometry. The results are as follows. (1) Taurine microinjected into AHA decreased blood pressure markedly. (2) The depressor response of taurine in AHA could be antagonized by propranolol, but not by phentolamine. (3) After microinjection of taurine into AHA, the content of norepinephrine in hypothalamus increased significantly. The above results suggest that taurine in AHA attenuates blood pressure by increasing the content of norepinephrine, probably mediated by beta-adrenergic receptor.