The Authors present the results of observations made between 1971 and 1974 on the incidence of human infection by Schistosoma mansoni at the Dique do Tororó in Salvador, Bahia, foiiowing sanitary improvements and biological control of vector snails by introduction of predatory fishes in the lake. Comparing these results with those obtained by other Author in 1960, it is concluded that the Dique do Tororó is no longer an important focus of schistosomiasis.