To investigate the cause of septicemia in patients with obstructive jaundice,the correlationship between intra-biliary tract pressure(IBTP),portal veinous flow rate(PVFR)and interleukin-2(IL-2),soluble interleukin-2 receptor(sIL-2R),T lymphocyte subpopulation in patient with obstructive jaundice(Group A)has been studied.Group A was subdivided into A1,emergency operation group;A2,elective surgery group;A3,patient’s age over 60 years and A4,age under 60.Ninety patients with simple gallstone(Group B)were also tested as a contrast.The result showed that of all Group A,CD3+,CD4+,CD8+ before operation were much lower than those 10 days after operation(Plt;0.05 or Plt;0.01),while the postoperative sIL-2R was significantly higher than that of 10 days after operation(Plt;0.01),in Group A1,emergency surgery,the preoperative sIL-2R was much more higher than that in others of the jaundice group(Plt;0.01).Corralation analysis showed IBTP was negatively corralated to IL-2,CD3+,CD4+,CD8+,but it had positive correlation with sIL-2R(Plt;0.01).PVFR was positively correlated to IL-2(Plt;0.01).These indicate that obstructive jaundice with infection is closely related to the decreased host immunity.