AbstractA new modification of silver staining of proteins in sodium dodecyl sulfate polyacrylamide gels is adapted to automated staining in PhastSystem Development Unit. The use of a reduction step, after fixation, with thiosulfate in alcoholic sodium acetate buffer results in a considerable increase in sensitivity without the need for a recycling step. The detection limit is tenfold lower than in the silver staining procedure recommended so far for PhastSystem and corresponds to 0.05–0.1 ng protein per band. Total staining time with the new procedure is 75 mi