This review examines the methods used to study carboxylic acids and the results of such studies on certain acids in freshwater snails. The three areas of carboxylic acid interest considered in this review involve their roles as metabolites, phagostimulants, and biomarkers. The chromatographic and non-chromatographic methods used to study the carboxylic acids in the snails are considered herein. The review places considerable emphasis on the role of carboxylic acids in uninfected Biomphlaria glabrata snails and those infected with Schistosoma mansoni.