Active psoriatic lesions have been investigated by direct immunofluorescence technique with polyclonal antisera to immunoglobulins and C3. We observed a cytoplasmic fluorescence of suprapapillary, suprabasally keratinocytes with tight topographical relationship to the parakeratotic horny layer. The intracellular deposits were IgA (in 60% of cases), IgG (53%), IgM (47%), C3 (30%). IgE und IgD have not been detected. The relationship of cytoplasmic protein deposition in vivo to parakeratosis is discussed briefly.