In summary, every patient presenting with a new (or recurrent) thromboembolic event should be carefully assessed for potential predisposing factors. This starts with a thorough patient history and complete physical examination. If indicated, the clinical assessment is then used to guide the clinical laboratory evaluation for a potential hypercoagulable state. Identification of a specific hypercoagulable state, primary or secondary, is extremely important in the prognosis and therapeutic management of the individual patient.