Extrahepatic cholestasis often evokes liver injury with hepatocyte apoptosis, aberrant cytokine production, and—most importantly—postoperative septic complications. To clarify the involvement of aberrant cytokine production and hepatocyte apoptosis in impaired resistance to bacterial infection in obstructive cholestasis, C57BL/6 mice or Fas‐mutated lpr mice were inoculated intraperitoneally with 10⁷ colony‐forming units of Escherichia coli 5 days after bile duct ligation (BDL) or sham celiotomy. Cytokine levels in sera, liver, and immune cells were assessed via enzyme‐linked immunosorbent assay or real‐time reverse‐transcriptase polymerase chain reaction. BDL mice showed delayed clearance of E. coli in peritoneal cavity, liver, and spleen. Significantly higher levels of serum interleukin (IL) 10 with lower levels of IL‐12p40 were observed in BDL mice following E. coli infection. Interferon γ production from liver lymphocytes in BDL mice was not increased after E. coli infection either at the transcriptional or protein level. Kupffer cells from BDL mice produced low levels of IL‐12p40 and high levels of IL‐10 in vitro in response to lipopolysaccharide derived from E. coli. In vivo administration of anti–IL‐10 monoclonal antibody ameliorated the course of E. coli infection in BDL mice. Furthermore, BDL‐lpr mice did not exhibit impairment in E. coli killing in association with little hepatic injury and a small amount of IL‐10 production. In conclusion, increased IL‐10 and reciprocally suppressed IL‐12 production by Kupffer cells are responsible for deteriorated resistance to bacterial infection in BDL mice. Fas‐mediated hepatocyte apoptosis in cholestasis may be involved in the predominant IL‐10 production by Kupffer cells. (HEPATOLOGY 2004;40:414–423.)