In a prospective study of 79 acute admissions of elderly patients to a Geriatric Unit, elevated alkaline phosphatase levels were commonly associated with the presence of extrahepatic bacterial infections. The changes were attributed to alkaline phosphatase liver isoenzymes. There was no significant change in aspartate transaminase levels or in bilirubin levels in infection. Such frequent abnormalities of alkaline phosphatase disproportionate to bilirubin and aspartate transaminase are not described in younger patients with infection. These findings may reflect age-related changes in liver function. In the same series, both bilirubin and albumin were predictors of outcome.