Introduction: Pseudothrombocytopenia (PTCP), caused by platelet (PLT) aggregation, is usually associated with ethylenediaminetetraacetic acid (EDTA)-dependent antibodies and cold aggluti-nins against PLT antigens. The aim of this study was to identify the PTCP and discover the most practical method to distinguish it from real thrombocytopenia. Methods: This study included 85 patients without hemorrhagic abnormalities and suspected PTCP. Blood samples containing EDTA, citrate and EDTA-kanamycin (KN) were analyzed at room temperature and 37 degrees C. Results: PTCP was detected in 24 of 85 patients. In 23 of 24 patients, EDTA-dependent pseudothrombocytopenia (EDTA-PTCP) was detected; 5 of whom had also the cold agglutinin-dependent PTCP. In only 1 of 24 patients, the cold agglu-tinin-dependent PTCP was found. In this study, no significant difference was observed in leukocyte counts comparing EDTA and citrate blood samples in cases with EDTA-PTCP. Conclusion: In clinical laboratories, a significant portion of the cases with low PLT counts was attributable to EDTA-PTCP and, therefore, did not require treatment. Even if these cases can be detected by bringing the blood samples containing EDTA to 37 degrees C or by adding KN to blood samples containing EDTA, the use of blood samples containing citrate taken for erythrocyte sedimentation rate analysis is a more practical priority method.