The study of hemostasis is a rapidly expanding field. Not only are new disorders being elucidated almost monthly, but also new proteins and interrelationships between known proteins are being reported continuously. These factors make the study of hemostatic disorders at once both exhilarating and challenging. New analysis techniques, such as chromogenic assays, ELISA assays, and molecular techniques, have advanced the study of hemostasis from the early days of tilt tube-based clotting tests. Further advancement in test automation will provide detailed analytic capabilities to smaller laboratories in the future. Additionally, continued advances in genetic testing will eventually allow us a detailed molecular view of a patient's hemostatic system previously unthinkable. This review has attempted to synthesize a very broad range of hemostatic physiology, laboratory testing, and pathologic disorders into a brief synopsis. Many details have unfortunately been excluded, but it is hoped that the nucleus of information presented on the recognition and diagnosis of hemostatic disorders will be valuable in the evaluation of patients with both simple and complex bleeding and thrombotic disorders.