The spontaneously hypertensive rat (stroke-prone) (SHRSP) experiences severe hypertension and cerebral hemorrhage. The serum cholesterol level in this rat is lower than that in the normotensive Wistar-Kyoto rat. Epidemiologic studies have indicated a negative association between serum cholesterol level and the incidence of cerebral hemorrhage in humans. Therefore the low level of serum cholesterol in SHRSP may cause cerebral strokes. The following investigation demonstrated that the activity for the biosynthesis of cholesterol is decreased in SHRSP due to the reduced activity of mevalonate pyrophosphate decarboxylase (MPD). However, the mechanism underlying the reduced activity of this enzyme remains unclear. In this review, we indicate that the level of MPD in the brain and liver of SHRSP is reduced from the age of 2 weeks.