This analysis of 80 patients with pyogenic hepatic abscess seen at this hospital demonstrated that there was no significant change in the incidence, age, sex, race, location or number of abscesses, symptoms, physical findings, labrotory data, routine roentgenograms, or complications over a 21 year period. However, there were relatively more women, the patients were older, and the incidence of appendicitis as an etiologic factor was much lower in this series than in the preantibiotic era. Ascending cholangitis was the most common etiologic factor throught this series, although malignant extrahepatic obstruction has become more prevalent in recent years. Escherichia coli remains the most commonly isolated organism, and gram-negative organisms are found in 72 per cent of the cultures. More than one organism was isolated in 65 per cent of the patients and there has been a significant increase in the number of anaerobic organisms isolated in recent years. Furthermore, a majority of anaerobic abscesses were solitary, and therefore, they had a better prognosis. The factors associated with a poor prognosis were age greater than 70 years, multiple abscesses, a biliary cause, an associated malignant condition, jaundice, an elevated serum glutamic-oxalacetic transaminase level, hypoalbuminemia, polymorphonucleocytosis, bactermia especially with multiple organisms, aerobic infection, and pulmonary, peritoneal, or other significant complication.