Objective: To investigate the influence of different biliary drainage methods on serum endotoxin level and immune function in rabbits with obstructive jaundice. Methods: Thirty-six New Zealand rabbits were equally randomized into sham operation group, external drainage group and internal drainage group. Rabbits in external drainage group and internal drainage group underwent establishment of reversible obstructive jaundice model, followed by obstruction removal and then internal and external biliary drainage respectively at 7 d after model was established, while those in sham operation group were subjected to two sham operations with the same time interval. Blood samples were collected before and 7 d after model establishment, and 7 d after drainage as well, and then the liver function parameters, serum endotoxin level and the ratio of CD4+CD25+ regulatory T cells in peripheral blood were determined. Results: No significant change was noted in any of the indexes at any time point in sham operation group (all P>0.05). In external drainage group and internal drainage group at 7 d after model establishment, the serum levels of bilirubin, transaminase and endotoxin were all increased, but the ratios of CD4+CD25+ regulatory T cells were decreased significantly compared with the levels before model establishment. At 7 d after drainage, the liver function parameters, serum endotoxin level, and ratio of CD4+CD25+ regulatory T cells were all significantly recovered in either external drainage group or internal drainage group compared with those at 7 d after model establishment, but the degrees of recovery of the latter two parameters in internal drainage group were greater than those in external drainage group (all P<0.05). Conclusion: Internal biliary drainage for obstructive jaundice is more beneficial than external biliary drainage in eliminating endotoxin and accelerating recovery of immune function.