Praziquantel ( PQT ) concentrations in plasma after iv 20 mg/kg decayed rapidly with tip of 0.36 h. The absorption of PQT was rapid following the intramuscular doses of 10,20,40mg/kg or intragastic dose of 100mg/kg, but the phase of elimination was much longer than that after iv. Both of MAT1m and MATig were greater than MRTiv. The bioavailability of ig was 13.2%, suggesting a strong first-pass effect. The kinetics of PQT elimination was linear after intramuscular dose of either 10 or 20 mg/kg, but nonlinear process was found when the dose was increased to 40mg/kg.By any route of iv, im and ig administration, the concentrations of PQT in the bile were much lower than the peripheral plasma concentrations and changed in parallel to the later with high levels after iv, medium levels after im and much low levels after ig.