A 63-year-old male presented thrombocytopenia, who had a history of EDTA caused pseudothrombocytopenia, then he was informed that thrombocytopenia caused by EDTA and should reanalyze platelet, aiming to count the platelet accurately. We performed the blood sample on Sysmex XE-2100 automated blood analyzer after taking venous blood in 5 minutes, but patient had normal platelet count 103×109 /L, peripheral blood smear showed no platelet aggregation (Figure 1A). Blood specimen tested again an hour late, with a results revealed platelet 33×109 /L. while the blood smear examined by microscope found platelet was moderately aggregated (Figure 1B). 90 minutes late, platelet detected again and the results was 32×109 /L. We reviewed the peripheral blood smear and found platelet aggregation was noticeable than ever (Figure 1C). As we know, EDTA caused pseudothrombocytopenia ( EDTA-PTCP ) is a type of thrombocytopenia that occur in vitro caused by a reaction between EDTA and harvested blood. It caused a spuriously low platelet count and lead to delay of surgery, unnecessary testing and potentially harmful treatment. Although it is an unusual finding on clinical practice, hematologist and laboratory technicians should be aware of EDTA-PTCP. We should performed the whole blood examination immediately for correct platelet results in those patients with EDTA-PTCP. In addition, other anticoagulants (citric acid, heparin) or manual microscopic platelet count could be optional to avoid error in platelet count.