This chapter basically talks about the approach to the patient with headache. Headaches are a common cause of pain and concern for many patients. When evaluating headache, it is especially important to assess whether the cause is a serious, or even life-threatening one. The most important aspect to approaching a patient’s headache is to obtain a thorough history. This information will guide the approach for evaluation and treatment. Several signs on physical examination of a patient with headache should raise the level of concern. These include abnormal neurologic findings, such as hemiplegia, dysarthria and altered mental status, as well as fever, significant hypertension, papilledema, anisocoria and meningismus. Laboratory values are also helpful in the evaluation of patients with headache. If any evidence of the history or physical examination is concerning for inflammatory process, these patients should have erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) tests ordered.