The aim of the present study was to evaluate paediatric reference values for platelet function using a point-of-care whole blood impedance aggregometry. METHODS, RESULTS & CONCLUSION: In 265 healthy infants and children aged <or=18 years aggregation was assessed on the Multiplate analyzer (Dynabyte, Munich, Germany), using arachidonic acid (ASPI: 0.5 mM), TRAP-6 (TRAP: 32 uM), collagen (3.2 ug), ADP (6.5 uM) and Ristocetin (Risto: 0.77 mg/ml) in isotonic saline prediluted (0.3 ml) hirudin-anticoagulated (25 ug/ml) whole blood (1.3 or 5 ml tubes). Aggregation was continuously recorded over five minutes. The increase of impedance due to the attachment of platelets to the electrodes was detected and transformed separately to arbitrary aggregation units (AU) plotted against time. Aggregation measured was quantified as area under the curve (AUC) of arbitrary units [AU *min]. Median [95%confidence interval] values and cut-off values (<or=5(th) and 10(th) age-dependent percentiles were shown. Following logarithmic transformation of baseline data variance analysis showed significant differences between age groups for induced aggregation with ASPI (p<0.001) and TRAP (p= 0.002). Overall, infants aged 0.1-12 months showed the lowest values compared with the remaining age groups. No gender differences were detected.