Abstract: We first found that monobromoacetates were active against Schistosoma japonicum.A series of monobromoacetates was prepared and screened for antischistosomal activity. Many of these compounds were found to possess pronounced activity against Schistosoma japonicum both in mice and in dogs.The compounds with a parasite reduction rate exceeding 90% were as follows:The following compounds were shown to possess 100% prophylactic effect against schistosomal infection.