The effects of chloride on stroke incidence and blood pressure were examined in salt-sensitive hypertensive rats. Stroke-prone spontaneously hypertensive rats (SHRSP) and Dahl salt-sensitive (DahlS) rats were fed on a 3% NaCl diet with or without 5% chitosan or 5% alginate, which have potent inhibitory effects on intestinal absorption of chloride and sodium, respectively. In SHRSP, the chitosan diet prevented stroke efficiently, whereas the alginate diet had no significant preventive effect. In DahlS rats, although the chitosan diet attenuated salt-accelerated hypertension, the alginate diet had no effect on blood pressure. In DahlS rats, 1h of feeding on the high-salt diet increased the serum chloride concentration and stimulated the activity of angiotensin converting enzyme (ACE), whereas no changes were seen in the group given the high-salt diet with chitosan. These results suggest that chloride induces stroke and hypertension in salt-sensitive hypertensive rats, concomitant with stimulation of serum ACE activity.