A retrospective study on patients with pyogenic liver abscesses was conducted to clarify the different clinical presentations among patients with Klebsiella pneumoniae abscesses and those with non-K. pneumoniae abscesses. From 1981 to 1993, the medical records of 146 adults with culture-confirmed pyogenic liver abscesses who attended Tri-Service General Hospital in Taipei were studied. Abscesses due to K. pneumoniae accounted for 114 (78%) of pyogenic liver abscesses. When compared to patients with non-K. pneumoniae abscesses, patients with K. pneumoniae liver abscesses had significantly higher proportions of monomicrobial infections, unknown sources of infection and solitary abscesses. Patients with K. pneumoniae liver abscesses were found to have diabetes mellitus more often than patients with non-K. pneumoniae liver abscesses (66% vs 19%). Septicemia was found more frequently in patients with K. pneumoniae liver abscesses than in patients with non-K. pneumoniae liver abscesses (50% vs 27%). The clinical presentations among the two groups were, otherwise, not significantly different. Regardless of the microbial etiology, patients with diabetes mellitus had longer periods of fever after treatment and hospitalization than patients without diabetes. The reason for the high relative frequency of liver abscesses in Taiwan and its more frequent occurrence in diabetes mellitus remains unclear.