The reversibility of blood-brain barrier (BBB) dysfunction was examined in rats after acute experimental hypertension. A short-lasting (≤4 min) acute hypertension was produced by intravenous injection of 20 μg/kg angiotensin. Evans blue, the barrier tracer, was administered intravenously either prior to or at intervals of 3, 10, 20, 30, and 60 min after the angiotensin injection. It was observed that the BBB dysfunction showed a peak 30 min after the angiotensin injection. Three of six animals that received Evans blue 60 min after angiotensin administration showed extravasation of the tracer on gross inspection. We concluded that BBB dysfunction may remain even 60 min after an acute hypertensive episode of short duration.