目的： 观察现场应用青蒿琥酯预防日本血吸虫感染的效果。方法： １９９７ 年７ ～９ 月， 分别在望江县杨河试区及贵池市沙山试区选择易感人群５６２ 例与２１８ 例， 将受试者随机分为两组， 按双盲法分服青蒿琥酯和安慰剂， 剂量均为６ ｍｇ／ｋｇ 顿服， 受试者在接触疫水后２ ｗｋ 开始服药， 每２ ｗｋ １ 次， 连服４ 次， 接受全程试验者末次服药后４ ｗｋ ， 用尼龙绢集卵法加改良加藤法进行效果评价。结果： 杨河试区服药组２７３ 例中２ 例孵化阳性，阳性率为０７ ％ ； 对照组２８９ 例粪检阳性１１ 例， 阳性率为３８ ％ ， Ｅ Ｐ Ｇ 为２６４０ ±１４９ 个。沙山试区服药组１０７例粪检均为阴性， 对照组１１１ 例粪检阳性７ 例， 感染率为６３ ％ ， Ｅ Ｐ Ｇ 为１４２３ ±２１４ 个。两试区青蒿琥酯预防血吸虫感染的保护率分别为８０９ ％ 与１００ ％ 。结论： 口服青蒿琥酯能有效地预防日本血吸虫感染。 Objective: To observe the effect of artesunate in preventing Schistosoma japonicum infection in the field. Methods: From July to September 1997, 562 and 218 cases of susceptible population were selected in Yanghe Trial District of Wangjiang County and Shashan District of Guichi City respectively. Subjects were randomly divided into two groups according to double-blind method The dose of artesunate and placebo was 6 mg / kg daily. The subjects started taking medication 2 wk after the exposure to water and once every 2 weeks for 4 consecutive times, and received the last dose After 4 wk, with nylon silk egg method plus improved Kato method for evaluation. Results: 2 of 273 cases in Yanghe test group were hatched positive, the positive rate was 07%. In the control group, 289 cases were stool positive, the positive rate was 38%, and the E P G was 2640 ± 149. In the test group of Shashan District, 107 cases were negative for stool test, while 111 cases for the control group were stool positive. The infection rate was 63% and the E P G was 1423 ± 214. The protection rates of artesunate against schistosomiasis in two experimental areas were 80.9% and 100% respectively. Conclusion: Oral administration of artesunate can effectively prevent Schistosoma japonicum infection.