OBJECTIVE: The aim of this study was to correlate the number of platelets in blood with the maximum clot firmness measured by thromboelastometry ROTEM analysis. MATERIALS AND METHODS: The results were obtained by routinely performed ROTEM analysis of blood samples (n=30) delivered from the Intensive Care Unit or OR to the Department of Clinical Laboratory Diagnostics. Thromboelastometry (ROTEM) was performed on citrated whole blood samples, with the corresponding reagent EXTEM, manufactured by Tem International GmbH, Munich, Germany. The number of platelets was determined as a part of the complete blood count in a EDTA blood sample by automatic hematology analyzer XN2100, Sysmex. Normality of distribution was analysed using the Kolmogorov-Smirnov test. Pearsons correlation coefficient was used to rate the correlation. Statistical significance was set at p<0.05 and analysis was performed using the statistical program MedCalc (version 11.1.0.0, MedCalc Software, Ostend, Belgium). RESULTS: Number of platelets were 103 81x109/L, and the maximum clot firmness (MCF) were 53 11 mm. Pearson's correlation coefficient between platelet number and maximum clot firmness (MCF) was r = 0.772 (p = 0.0001, 95% CI from 0.5711 to 0.8861). CONCLUSION: Maximum clot firmness measured by thromboelastometry (ROTEM) moderately correlates with the number of platelets in the blood. Therefore, it cannot be used for reliable estimation of the platelet number. This supports the fact that TEM is global coagulation test as it measures the contribution of numerous hemostasis factors involved in clot formation, and not only platelets.