Summary In this paper, the correlation beween the bile duct and the hepatic venous and lymph system in dogs was observed under the regurgitation experiments and BSP retention. (1) When the pressure in bile duct was increased slightly above the normal (at the slow dropping period), the regurgitation of materials through the hepatic cell was probably due to the perfusion and their concentration in the lymph was mach higher than in the blood. At the same time, increasing the resistance of portal circulation was observed. (2) During the regurgitation experiments, it was observed that elevating the pressure in bile duct above a certain level (about 500 mmH2O) may brought to rupture of smaller bile duct, and there was rapid increase in drops of materials through the irrigator. The pressure was lowered again to original level, however, the regurgitation of the materials also returned to the original rate. (3) In bile duct ligated dogs, the pressure in bile duct was increased to a mean of 455 mmH2O at a week after ligation of the common bile duct, but rather decreased to around 300 mmH2O, as same as the maximum pressure for bile secretion in normal dog, at a month after the ligation. It seems, therefore, that the rupture of the bile duct was may occured in early period of the biliary obstruction, if it exist, but may returned to normal state in the later period. (4) Studies with BSP retention indicated that the communication of the lymph system to bile duct and blood vessel was rather impaired in the later period of biliary obstruction. (5) In the dogs damaged by CCl4, increasing the permiability of liver cell was observed.