Children cannot be considered as miniature adults regarding to hemostatic balance. There is a great difference between neonatal, pediatric, and adult hemostatic systems. The concept of developmental hemostasis is now accepted on a wide range. It ensures accurate prevention, diagnosis, and treatment of thrombotic and hemorrhagic diseases in neonates and children. Developmental hemostasis could affect multiple physiological processes within the body other than hemostasis, such as angiogenesis, inflammation, and wound repair, as well as the interaction between different drugs and the coagulation system. “The Perinatal and Pediatric Hemostasis Subcommittee of the Scientific and Standardization Committee of the International Society on Thrombosis and Hemostasis (ISTH)" recommended for each laboratory to define reference ranges which are age-adjusted using its own technical conditions. Adding to that, accurate sampling techniques are mandatory for correct interpretation of laboratory results. New assays should be developed putting into consideration the fundamentals of developmental hemostasis.