Evaluation of the dizzy patient in the prehospital setting is a challenging task. A chief complaint of feeling lightheaded or dizzy is extremely common. Traditionally, dizziness is often subdivided into four different categories: lightheadedness, presyncope, disequilibrium and vertigo. It can be further subdivided into orthostatic dizziness and positional dizziness. This chapter discusses the physiology, categories, and key challenges of dizziness. In order to successfully approach patients who are complaining of dizziness, the EMS professional needs to understand how the brain perceives orientation in space and processes the signals to maintain an upright posture. He should focus on identifying life-threatening entities, including serious cardiac dysrhythmias or cardiac syncope; centrally mediated causes of vertigo; and life-threatening metabolic/electrolyte derangements. Obtaining a blood glucose level, acquiring a 12 lead ECG and performing a focused physical exam may help identify a subgroup of patients with immediately life-threatening conditions.