The literature was reviewed to obtain data from 11 mammalian species on liver weight, hepatic blood flow, and antipyrine intrinsic clearance. It was demonstrated that liver weight and hepatic blood flow in all species could be readily related to body weight by a simple equation. Additionally, hepatic blood flow in all species was directly proportional to liver weight. With the exception of man, antipyrine intrinsic clearance was also directly proportional to liver weight. Man's intrinsic clearance was approximately one-seventh of that which would be predicted from other species. Data on benzodiazepines and phenytoin showed a similar pattern.