Rats experimentally infected with 30 meiacercariac clonorchius sinensis were treated with Leyo-praziquaatel (L-PQT) and Dex-tro praziquantel (D-PQT) in dosage of 10img/Kg twice daily for two days and killed 7 days after treatment. In L-PQT group no worms were found. The cure rate was 100%; while in D-PQT group and control group

the average numbers of worms were 6.6±2.72 and 8.4±5.97

respectively. The efficacy of L-PQT was superior to D-PQT(P<0.01)

while difference of efficacy between D-PQT and control group was not significant(P>0.05).Thirty-seven patients were treated with L-PQT in dose of 25mg/kg 3 times a day

total dosage of 75mg/kgo Following stool examinations of 32 patients 3 months after treatment showed that egg negative conversion rate was 71.88%(23/32)

while nine of stool egg positive patients showed the average egg ceduction rate was 98.6%.Side reaction of L-pQT were mild and transient. Blood and urine routine

liver function test and electrocardiograph examination skowed no remarkable changes before and after treatment