My research investigates red blood cells participation in hemostasis. Red blood cells are considered passive bystander in the coagulation process. However, they affect the clot properties, and a coagulation factor (FXIII) promotes their retention. Therefore, our hypothesis is that red blood cells have an active role in hemostasis. I focus to identify interaction between the red blood cells and other components of blood clots to explain their inclusion and retention in clots.