Platelet to leukocyte adhesion phenomena (PLAP) and the phagocytosis of platelets by neutrophils from the EDTA anticoagulated blood samples are described. PLAP was transferable to a normal blood specimen by patient’s plasma or serum with or without complement. Further studies revealed in vitro evidence of hereditary platelet dysfunction. In vivo study of platelet survival and in vitro analysis of platelet membrane glycoproteins were normal. We conclude that PLAP can be seen in an asymptomatic individual with in vitro evidence of hereditary platelet dysfunctio