The changes of the bile ducts were reciewed retrospectively in 38 patients of clonorchiasis by ultrasonography and/or CT. Diagnosis was made in 13 patients by cholecystectomy and exploration of the common bile duct another 2 patients by segmentectomy and wedge resectionof the liver and 23 patients by stool examination, 14 of 36 cases showed the parallel channel signs and small nodular echoes around the dilated bile ducts And 3 cases showed the echoes of worm of clonorchis sinensis in the common bile duct. 22 of 36 cases showed the parallel channel sighs only. All cases (11) done CT showed diffuse dilatation of the peripheral bile ducts. 5 of 11 cases showed ring or tubular contrast enhancement around the dilated bile ducts. In 2 cases of liver resection the bile ducts showed adenomatous hyperplasia and severe periductal fibrosis. Proliferation of blood bessels and infiltration of inflammatory cells were also seen, So we consider that the increased echoes of the bile duct wall small nodular echoes aroud the bile ducts were attributed to the bile duct dilatation severe adenomatous hyperplasia and periductal fibrosis. the ring or tubular contrast enhancement of the dilated bile ducts seems to becaused by the marked periductal inflammation resulting in capillary proliferation and the periductal fibrosis.