A novel technique for immunocytochemical demonstration of taurine (Tau) is presented. Antisera raised against Tau conjugated to protein by glutaraldehyde (GA) react selectively with similar conjugates in model systems and in tissue fixed with GA. In rat cerebellum, Tau-like immunoreactivity is high in the Purkinje cells but low in other cell types, including the stellate cells for which Tau has been proposed as transmitter.