Bacterial or pyogenic liver abscess does not represent a specific liver disease, but rather a final common pathway of many pathologic processes. In the preantibiotic era, liver abscesses were typically the sequelae of unchecked appendicitis. In such cases, prompt surgical drainage offered the only hope for cure. Many advances, including the development of antibiotics, recognition of the role of anaerobic bacteria, the advent of noninvasive imaging, and the use of nonsurgical drainage have improved this once bleak outlook. By improving treatment of underlying diseases that once led to abscess formation, these advances also have transformed the epidemiology and presentation of pyogenic liver abscess. The classic triad of fever, right upper quadrant pain or fullness, and jaundice resulting from advanced pylephlebitis seldom is seen now. Despite these changes, pyogenic liver abscess remains an important clinical entity for which prompt recognition and treatment are essential for a favorable outcome.