W e report a patient with pseudo gray platelet syndrome. He was admitted to our hospital because of acute myocardial infarction. He had platelets that were stained poorly and appeared gray and agranular under a light microscope. This appear-ance is a characteristic feature of gray platelet syndrome. However, in this case, no bleeding tendency was observed and the abnormality was dependent on the presence of ethylenediamine tetra acetic acid (EDTA) and did not occur in a nonantico-agulant, trisodium citrate dihydrate and heparin. There are few reports of this pseudo gray platelet syndrome and, in fact, this is the first report of the syndrome in Japan, possibly because the phenomenon has been unrecognized and passed over in the past.Int J Hematol. 2002;76:376-378.