We would like to reply to comments made by Kozek-Langenecker and Scharbert regarding our article on fluid-related side-effects on standard coagulation tests and functional hemostasis analyses in children. The authors criticised the fact that albumin, gelatine and hydroxyethyl starch 130/0.4 (HES) were all administered at equal amounts of 15 ml.kg−1 and stated that the known difference in volume-expanding effects of these solutions would explain the reported findings. We are aware of the different volume-expanding effects of the tested solutions, which, however, are primarily related to differences in molecular size, and thus differences in elimination. We therefore performed analyses immediately after administration in order to avoid pronounced influences of volume expansion. Moreover, as shown in our Table 1, the results of concentration-dependent analyses (Hb, platelet count, fibrinogen concentration, AT, FXIII) declined similarly after administration of all fluids, thus confirming a comparable dilutional state. The authors further asked about the rationale for choosing fibrinogen/fibrin polymerisation (FIBTEM® MCF) for sample size calculation and mentioned that this variable did not significantly differ after gelatine or HES 130/0.4 administration. FIBTEM® MCF was chosen because previous studies have clearly demonstrated that colloids primarily interfere with fibrinogen/fibrin polymerisation, especially at the dilutional stage investigated by us. It is correct that direct comparison showed no statistically significant difference for gelatine vs hydroxyethyl starch with regard to fibrinogen/fibrin polymerisation, but this was also true for hydroxyethyl starch vs albumin, while no difference was observed between albumin and gelatine. In addition, the α angle was significantly lower for HES than for albumin, while no difference was observed for gelatine. CT values were prolonged only for HES. Moreover, speed of clot formation was significantly prolonged for HES as compared to albumin or gelatine. The authors also stated that no treatment of impaired haemostasis was needed. However, this assumption refers only to the immediate post-infusion period, while several children, of course, needed administration of coagulation factors and even platelets during their further intra-operative course. As the need for haemostatic therapy was beyond the aim of the study, we did not provide these data. Lastly, the authors mentioned that the newer starches should impair coagulation to a lesser extent than do the older starches, as used in the referenced study by Wilkes. Nevertheless, recent published works prompt questions on this topic [1, 2], and further data will be needed to finally answer the question as to the intrinsic effects of the various HES solutions.