Objectives: Establishment of reference intervals (RI) of global clotting tests and the most common bleeding parameters for the paediatric population with respect to age and sex, taking into account the method, analyser and reagent used and to compare the obtained values with the indirect method of determining RI. Patients and Methods: Data for coagulation parameters: prothrombin time (PT; s), activated partial thromboplastin time (APTT; s), thrombin time (TT; s), fibrinogen activity (Fbg; g/l) factor VIII (FVIII; %), factor XIII (FXIII; %), von Willebrand factor (VWF:Ac; %), antigenic concentration of von Willebrand factor (VWF:Ag; %) and collagen binding activity of von Willebrand factor (VWF:CB; %) were collected retrospectively from laboratory information system over five years (2015-2021). Only laboratory results of healthy subjects (N = 1000) aged 1-18 years determined on STA-R analysers were taken into account. The first group (N = 250) covers the age group of 1-5 years, the second (N = 248) of 6-10, the third (N = 242) of 11-14 and the fourth group (N = 260) of 15-18 years. In all subjects, RI was determined according to the Clinical Laboratory Standard Institute guidelines (CLSI) – using direct a posteriori approach. Furthermore, the obtained values were compared with the RI values obtained by the indirect method (N = 12348). Results: Of the global coagulation parameters, only RI for PV did not show a statistically significant difference between girls and boys (P = 0.111). A statistically significant difference in RI between age groups was shown for PV and aPTV (P < 0.0001 and P = 0.007). The reference intervals of FVIII and FXIII did not differ statistically significantly between age groups (P = 0.078 and P = 0.082), while for FXIII there was a significant difference according to gender (P = 0.038). A statistically significant difference in RI was proved for all three parameters of vWF for group 4 in relation to other groups (P = 0.029, P = 0.005 and P = 0.009). Further, indirect estimation of RI for global coagulation system tests resulted in statistically indistinguishable differences in RI relative to RI obtained by the direct method. Conclusion: Reference intervals vary considerably depending on age, method, manufacturer, and reagent used. Reference ranges specific to age/gender as well as analyser/reagent system must be used to ensure proper assessment of haemostasis in children. Reference intervals obtained using the indirect method are comparable to the RI obtained by the direct method.