Tobacco cells were stained for peroxidases by exposing them to a mixture of p-phenylenediamine and H₂O₂. Peroxidase activities were mainly associated with nuclei, nucleoli, plasma membranes and cell walls. Starch gel electrophoresis of the protoplast extracts indicated that moderately migrating anionic isoperoxidase A₂ and fast migrating A₃, A₄ were secreted into cell walls and media. Only vacuole contained all four major cationic isoperoxidases C₁, C₂, C₃ and C₄. It was also learned that moderately migrating C₁ and C₂ were present in the nuclei extracts, whereas chloroplasts contained fast moving C₃ and C₄. Interestingly, very slow migrating anionic isoperoxidases A_a and A₁, which are also secretory peroxidases, were present on the protoplasts, nuclei, and chloroplasts.