In this work the occurence of Biomphalaria tenagophila naturally parasited by evolutive forms of Schistosoma mansoni is registered in the city of Peruibe, situated in the Southern Littoral of the State of São Paulo (Brazil). Besides B. tenagophila, in the region it occurs also Drepanotrema cimex, a species not proved to be a host of Schistosoma mansoni and whose occurence had not yet been recorded in Peruibe.