Despite existing guidelines for preoperative laboratory diagnosis of hemostasis, routine preoperative coagulation testing still represents a controversially discussed part of the preoperative patient assessment. Improvement of perioperative outcome by preoperative screening coagulation tests could not be confirmed by numerous studies. Therefore, in adults, coagulation testing should depend on parameters like patient history, ASA classification, type of operation, and age. In children a bleeding history is not always available, so a step by step procedure is indicated.