A high-performance liquid chromatographic method utilising fluorimetric detection of oxidised and reduced glutathione, following derivatization with dansyl chloride is described. Dansyl derivatives are separated on an aminopropyl silica column with a methanol-sodium acetate gradient system giving detection limits (signal-to-noise ratio = 2) of 1 pmol. This is in the order of 100-fold more sensitive than established methods based on the ultraviolet detection of dinitrophenylglutathione derivatives. The present procedures have been used to determine oxidised and reduced glutathione in rat lung tissues and in alveolar macrophages.