Abstract: In a preceding paper of this series, we reported the synthesis of alcoholic and phenolic esters of monobromo- and monoiodoacetic acid which were found to possess schistosomicidal activity both in mice and in dogs. In order to search for more active schistosomicidal drugs, twenty-two coumarin esters of monobromo-and monoiodoacetic acid were prepared and tested for schistosomicidal activity. In screening with mice, 21 compounds were found to possess schistosomicidal activity, among which 3-(2'-bromoacetoxy ) coumarin and 4-methyl- 6,7-bis- (2'-bromoacetoxy) coumarin were shown to be the most effective and their worm reduction rates reached 100%.