OBJECTIVES The first objective of this research is to verify the reference intervals received from the manufacturer of the platelet function analyzer PFA-200. The second objective of it is to determine the activity of the von Willebrand factor and to examine the correlation between it and the results of the analysis on the PFA-200. STUDY DESIGN The study was conducted as a cross-sectional study. PARTICIPANTS AND METHODS The study included 20 voluntary participants without acute and chronic diseases who did not take medications which could affect the study results ten days before blood draws. The time required for platelet plug formation (closure time, CT) was measured in whole blood samples of volunteers on the platelet function analyzer Innovance PFA-200 with test cartridges COL/EPI and COL/ADP. The von Willebrand factor activity was determined in blood plasma samples on the Sysmex CS-2500 device with the Innovance VWF Ac reagent. The results were processed by the statistical program MedCalc. RESULTS The results of the platelet function analysis with COL/EPI and COL/ADP test cartridges on the PFA-200 were compared with reference intervals received from the manufacturer. The CT value of 18 out of 20 samples from both analyses fit into the recommended reference intervals. Reference intervals of 85 - 165 s for COL/EPI and 71 - 118 s for COL/ADP were verified. The von Willebrand factor activity was determined, and its correlation with the results from the PFA-200 was examined. The resulting correlation factors are rho = -0.632 for COL/EPI and rho = -0.588 for COL/ADP. 8. SUMMARY 20 CONCLUSION Verification of reference intervals received from the manufacturer of the platelet function analyzer PFA-200 was successful, and all tested reference intervals were accepted. A negative correlation between the von Willebrand factor activity and analysis results from the PFA-200 was confirmed.