Mevalonolactone (ML) is a lactone form of mevalonic acid (MA), they exist in equilibrium. Mevalonolactone is used to study the effect of statin on the prenylation of Ras and Rho GTPases. Recently was discovered, that mevalonolactone disrupted mitochondrial functions and induced permeability transition pore opening in rat brain mitochondria, what can be important for the pathogenesis of mevalonic aciduria. Mevalonic aciduria is caused by severe deficiency of mevalonic kinase activity leading to tissue accumulation and high urinary excretion of mevalonic acid and mevalonolactone. It was proved that ML impaired essential brain mitochondrial functions with the involvement of MPT pore opening and that disturbance of brain mitochondrial homeostasis contributed to the neurologic symptoms of MVA.