Ribosomes from vegetative cells and spores of Streptomyces griseus have been used to prepare ribosomal proteins for polyacrylamide gel electrophoresis. Differences in the gel electrophoretic profile of proteins from vegetative cells and spore ribosomes can be detected. Spore ribosomes were stable during the isolation process, but in the case of vegetative cell ribosomes it was necessary to use protease inhibitor to obtain reproducible results. Suspensions of washed ribosomes of vegetative hyphae have higher proteolytic activity than ribosomes from spores.