Hypertensive crises are commonly observed in an emergency room. Regardless blood pressure values, hypertensive crises are classified in emergencies, characterized by life-threatening acute organ damage, and urgencies, with no evidence of acute or progressive organ injury. In an hypertensive emergency an appropriate and immediate management with parenteral drugs is mandatory, while in an hypertensive urgency blood pressure should be decreased within 24-48 h with orally active agents. This article reviews the spectrum of clinical syndromes that comprise hypertensive emergencies, focusing on specific drugs and therapeutic strategies available in the emergency department, based on current literature. Since no randomized prospective trials are available, an evidence-based approach recommending an optimal therapeutical management is not possible. Much of the therapy is therefore entirely empirical and based on the underlying pathophysiologic and clinical findings. Further studies are needed to clarify pathophysiologic mechanisms in order to optimize therapeutic approach.