Adding potassium to normal chow reduces death rate in hypertensive stroke-prone (SHRSP) rats from 83 to 2%, a 98% reduction. An 86% reduction in deaths occurred even when blood pressure (BP) was virtually equal in the two SHRSP groups being compared. Potassium supplements in the diet also reduced stroke deaths in hypertensive Dahl S rats from 55 to 4%, a 93% reduction. There was an 87% reduction in deaths even when BP was actually equal in the two Dahl S groups being compared. The added potassium in the diets decreased BP moderately in SHRSP rats and modestly in Dahl S rats, which contributed somewhat to the reduction in strokes. However, more importantly, the added potassium seems to reduce the intrinsic susceptibility to cerebral artery lesions for a given level of hypertension, even when BP is not lowered.