The unconscious patient presents an challenging emergency in the intensive care unit. Patient evaluation and treatment must occur simultaneously. After checking vital signs, deciding about cardiopulmonary resuscitation or intubation, an intravenous line must be established, blood samples collected and glucose and thiamine should be given. The physical and neurological examination should be performed in a efficient way and must consider the following eight points: best reaction to loud commands, best motor reaction to noxious stimuli, respiratory pattern, size and reactions of pupils, eye movements, corneal and blink reflex, meningismus, muscle tone and deep tendon reflexes. With this approach it is possible to formulate a working diagnosis, and the appropriate diagnostic steps can be performed.