1. We showed that a nutritional factor was able to attenuate the development of hypertension and its related diseases in stroke-prone spontaneously hypertensive rats (SHRSP). In the present study, the effect of Wakame, an edible brown seaweed, on the development of stroke was examined in SHRSP. 2. We studied the treatment with 5% (w/w in a diet) Wakame powder in salt-loaded (0.5% NaCl in drinking water) SHRSP. Salt-loaded animals treated with 5% cellulose or kaolin were used as controls. Wakame significantly delayed the development of stroke signs (P < 0.05) and significantly improved the survival rate of salt-loaded SHRSP (P < 0.05). There was no significant difference in the elevation of blood pressure among the three groups during the observation period. 3. We isolated fucoxanthin, a carotinoid, from Wakame powder and studied its preventive effect on ischaemic cultured neuronal cell death. Fucoxanthin significantly attenuated neuronal cell injury in hypoxia and re-oxygenation (P < 0.05). 4. Based on these results, we conclude that Wakame has a beneficial effect on cerebrovascular diseases in SHRSP, independent of hypertension. It is possible that fucoxanthin in Wakame may have a preventive effect against ischaemic neuronal cell death seen in SHRSP with stroke.