Abstract: Artesunate (dihydro-artemisinine hydrogen succinate, coded as 804), one of the derivatives of reduced qinghaosu, was demonstrated to exert antischistosomal effect in experimental animals infected with Schistosoma japonicum.When infected mice were treated orally with artesunate suspension at the total dosage of 450～900 mg/kg in 1～3 days, the total worm reduction rates were 60.6～70.6% and the female worm reduction rates were 83.0～91.0%. If its sodium salt (coded as 804-Na) was given intraperitoneally to infected mice at dosages of 100～120 mg/kg/day×3, the worm reduction rates were 33.8～43.3% and the female worm reduction rates were 57.4～76.5%. When infected rabbits were treated orally with artesunate suspension and its sodium salt at dosages of 80～120 mg/kg/day×4～6, the worm reduction rates were about 50%; with its sodium salt or its PEG solution given intramuscularly at dosages of 50～100 mg/kg/day×4, the total and female worm seduction rates were 59.2～67.2% and 76.9～95.4% respectively.Artesunate was shown to be effective against 1-week-old immature worm. No severe side effect was observed in animals treated with artesunate.