From January 1996 to April 2002, a total of 248 patients with pyogenic liver abscess were enrolled in this study. Abscesses caused by Klebsiella pneumoniae accounted for 69% (171) of cases. Abscesses caused by K. pneumoniae were more strongly associated with diabetes mellitus or impaired fasting glucose than liver abscesses caused by non-K. pneumoniae (70.2% vs 32.5%). Solitary abscess and monomicrobial isolates were more frequent in the K. pneumoniae group than that in the non-K. pneumoniae group. A total of 42 patients were treated with antibiotics alone. Antibiotics treatment was combined with other procedures, including single aspiration in 23 patients, percutaneous drainage in 176 and surgical drainage in 7. A higher incidence of metastatic infections occurred in the K. pneumoniae group than in the non-K. pneumoniae group (14.6% vs 3.8%). By contrast, the mortality rate of the K. pneumoniae group was lower than that of non-K. pneumoniae group (4.1% vs 20.8%). There was no significant difference in the relapse rate between these 2 groups (6.5% vs 6.4%). We also found that the presence of respiratory symptoms (including cough, dyspnea, or chest distress), size of abscess > or =5 cm in diameter and non-K. pneumoniae pathogens were significant prognostic factors for mortality.