The effects of various chemical substanceson the permeability of plasma membranesand tonoplasts of three suspension cultures (Catharanthusroseus, Thalictrum rugosum and Chenopodiumrubrum) have been studied. The permeabilityof the plasma membrane is monitoredby measuring the activity of the cytosolic enzymeisocitrate dehydrogenase and the permeability ofthe tonoplast is measured by determining the releaseof substances stored in the vacuoles (inorganicphosphate, berberine and betanin for thethree cell lines, respectively). The minimum concentrationrequired for quantitative release of vacuolarproducts have been established for five differentpermeabilization agents. Cell viability islost upon permeabilization except for treatmentof Catharanthus roseus with DMSO and Triton X-100.