Establishing an open and honest physician-patient relationship is essential for the proper evaluation and management of headache disorders. Obtaining a complete headache and medical history is the most important part of the initial diagnostic evaluation. This history should include information about headache onset, pain intensity, character of the pain, presence of aura, associated autonomic symptoms, and trigger factors. Special attention must be paid to the frequency of analgesic use, both prescription and over-the-counter, to identify analgesic rebound headache. A thorough neurologic examination must also be performed; if it is normal, there is usually no need for special tests. Headaches are classified as either primary or secondary. Primary headaches have no structural or metabolic cause, while secondary headaches are caused by an underlying pathologic or metabolic process. Migraine, tension-type, cluster, and analgesic-rebound headaches are all primary headache disorders. Secondary headaches are caused by conditions such as increased intracranial pressure, pseudotumor cerebri, subdural and intracerebral hematomas, hypertension, meningitis, temporal arteritis, Lyme disease, and brain tumors. Accurate diagnosis of headache is essential to determine the appropriateness of further testing and to guide proper treatment of the patient's condition.