AbstractAs ABO blood type influences the plasma level of coagulation factor VIII (FVIII), it likely also affects activated partial thromboplastin time (aPTT) and thrombin generation assay (TGA) values. Here, we aimed to investigate the effect of ABO type on the normal values of three global coagulation assays: prothrombin time (PT), aPTT, and TGA.PT, aPTT, TGA [1 or 5 pmol/L tissue factor (TF)], coagulation factors, anticoagulation factors, and ABO type were measured in 200 healthy adults.aPTT was significantly prolonged in those with type O compared with those with type non-O, whereas PT was not significantly different between those with type O and type non-O. The time to peak induced by 5 pmol/L TF was significantly prolonged, and the peak thrombin level was decreased in those with type O compared with those with type non-O. FVIII was a major contributor to the ABO-specific reference range of aPTT, 5 pmol/L TF-induced time to peak, and peak thrombin level.The reference ranges of aPTT and TGA (time to peak and peak thrombin level) differed by ABO type. FVIII level is considered a major contributor to ABO type-specific differences with respect to aPTT and TGA.