Human serum paraoxonase is responsible for the hydrolysis of organophosphate anticholinesterases, however, whether the enzyme has a physiological role other than the detoxication of insecticides and nerve gases has remained uncertain. Recently, evidence has begun to accumulate of a relationship between the serum activity of paraoxonase and atherosclerosis. Paraoxonase may a fundamental role in lipoprotein metabolism, preventing oxidative changes to low-density lipoprotein which render the particle atherogenic.