Sixteen psoriatic patients and 11 control subjects were investigated by immunofluorescence for skin immunoglobulins (IG) and complement (c) deposits and for keratinocyte membrane markers with anti beta 2 microglobulin (beta 2 m) antibodies (Ab), Con A, and pemphigus Ab. IG and/or c deposits were almost constant in involved epidermis. Three patterns were associated: (1) parakeratotic nuclear (dots-dashes), (2) stratum corneum (SC) intercellular (lamellar pattern), (3) vascular (granular or linear deposits in papillary dermal vessels). In uninvolved epidermis nuclear or vascular deposits could occasionally be present but intercellular pattern was never found in SC. Control specimens were always negative. The three surface markers investigated (beta 2 m, Con A receptor, Pemphigus antigen) could be demonstrated on psoriatic keratinocytes with only slight differences in distribution when compared with controls. Thus, by this methodology no important abnormality could be found in psoriatic keratinocyte membrane antigens.