A reverse-phase HPLC spectrofluorometric method was developed for routine, specific and fast analysis of glutathione (GSH) in biological materials based on modified O-opthaldialdehyde derealization procedures. The developed method allowed the determination of glutathione in yeast biomass, bile and plasma samples from goats. The limit of detection was estimated to be 8 µМ for yeast biomass at a signal to&noisc ratio of 1 and was further extended to signal ratio of 2, which allowed the detection of lower amounts of GSH in the bile and plasma up to 10 ng/cm3 The methods ol GSH extraction from biological materials, derivatization procedures and separation by HPLC method were reported.