Food-borne trematodiasis is an emerging public health problem and there is a need to develop novel treatment options. We examined the in vivo efficacy of single oral doses of artesunate and artemether administered to rodents experimentally infected with either Clonorchis sinensis or Opisthorchis viverrini. Rats infected with adult C. sinensis were administered artesunate or artemether at doses of 75, 150 or 300 mg/kg. Hamsters infected with adult O. viverrini were administered artesunate or artemether at doses of 200, 400 or 600 mg/kg. Treatment efficacy was assessed according to reductions in worm burden compared with infected but untreated control animals. Worm burden reductions of 98.6-100% were found in C. sinensis-infected rats after a single dose of artesunate and artemether at 150 mg/kg. Administration of artesunate and artemether at a dose of 400mg/kg to O. viverrini-infected hamsters resulted in worm burden reductions of 77.6% and 65.5%, respectively. However, both drugs showed toxic effects when administered to O. viverrini-infected hamsters at a dose > or =400mg/kg. Our study demonstrates that artesunate and artemether possess excellent clonorchicidal activities in vivo. These findings provide a foundation for subsequent clinical trials. More laboratory investigations are warranted to investigate further the opisthorchicidal properties of the artemisinins.