Patients with severely increased blood pressure often present to the emergency department. Emergency physicians evaluate and treat hypertension in various contexts, ranging from the compliant patient with well-controlled blood pressure to the asymptomatic patient with increased blood pressure to the critically ill patient with increased blood pressure and acute target-organ deterioration. Despite extensive study and national guidelines for the assessment and treatment of chronically increased blood pressure, there is no clear consensus on the acute management of patients with severely increased blood pressure. In this article, we examine the broad spectrum of disease, from the asymptomatic to critically ill patient, and the dilemma it creates for the emergency physician in deciding how and when in the process to intervene.