Background/aim: Ankaferd hemostat (ABS; Ankaferd blood stopper, İstanbul, Turkey) is a prohemostatic agent affecting erythrocytes.The hemostatic action of ABS depends upon fibrinogen gamma chain, prothrombin, and red blood cells. The aim of this study was toassess the effects of ABS on erythrocyte aggregation via hemorheological analyses.Materials and methods: To measure erythrocyte aggregation, blood samples were obtained from healthy, nonsmoker volunteers whohad not taken any medication in the previous 10 days. One mL of blood was placed into the laser-assisted optical rotational cell analyzer(LORCA), into the chamber formed by the gap between two concentric glass cylinders. The solution prepared with ABS and saline wasadded to blood in incremental amounts of 10 µL, 20 µL, 30 µL, 40 µL, 50 µL, 60 µL, 70 µL, and 100 µL. Erythrocyte aggregation wasdetermined by laser-assisted optical rotational cell analyzer at 37 °C.Results: AMP was found to be 17.7 ± 2.1 au in the blood without ABS, whereas it was lower in the blood with ABS. AMP was 16.0 ±3.3 in the ABS-added blood group. RBC aggregates did not form faster when cells contacted ABS. The t t½ value was 4.6 ± 2.6 in theABS-added blood group and 1.9 ± 0.20 in the control group. Aggregation was faster in the control group (P = 0.03). AI, which is acombination of AMP and t½, was lowered in the ABS group (48.7 ± 12.3) compared to the control group (65.8 ± 1.6) (P = 0.02). It wasnotable that the γIsc max (sec-1) value of the control was higher (200 ± 106) than the ABS-added blood group (141 ± 51.0).Conclusion: ABS has antierythroid aggregation effect. ABS inhibits pathological aggregation of red blood cells. Antithrombotic clinicaleffects of ABS may be ascribed to the antierythroid aggregan actions of the drug.