Pathological modifications in structure at the cell wall – plasmalemma interface are common in diseased plant tissues. These modifications vary from small, localized structures which invaginate the protoplast to large, irregularly contoured elaborations which envelop haustoria. Some published electron micrographs suggest that the plasmalemma may be discontinuous in areas adjacent to modified cell walls. Structural changes in cell walls, similar to those in diseased plants, are common in plant roots exposed to uranyl acetate. In such roots, the plasmalemma appeared distinctly discontinuous in cells with highly modified walls, whereas it was continuous in adjacent cells with little or no wall modification. In both types of cells, internal membranes and organelles appeared normal. This suggests that the breaks seen in the plasmalemma were not fixation artifacts. In untreated roots, apparent discontinuities in the plasmalemma were observed only in secretory outer root cap cells which contained masses of mucilaginous material between the wall and protoplast. Since uranyl treatment does not increase the rate of electrolyte loss from tissue, these observations suggest that modified cell walls may assume some of the permeability functions usually attributed to the plasmalemma.