Taurine levels in the brain decrease when an animal is subjected to pathological conditions, such as ischemia-anoxia and seizure, but they tend to increase in hypertension. The present study investigated the blood-brain barrier (BBB) transport of [3H]-labelled taurine in spontaneously hypertensive rats (SHR) using internal artery carotid perfusion (ICAP) at a rate of 4 ml/min for 10, 15 and 30 seconds. The volume of distribution in brain (VD) and the permeability surface area product (PS) of [3H]-taurine through the BBB in SHR were calculated. The PS value for taurine at 15 s was higher than at the longer perfusion times. This could result from taurine efflux back into blood occurring after 15 s. As in the case of normotensive rats, taurine was shown to enter the brain via the sodium and chloride ion dependent carrier system.