The Glasgow Coma Scale (GCS) has been the gold standard for assessing the level of consciousness in patients with significant brain injury. Prior efforts to modify or replace this scale have been unsuccessful because no scale could improve on its simplicity and practical usefulness. This review provides a historical perspective on coma scales and introduces a new and simple, but more comprehensive, scale: the Full Outline of UnResponsiveness (FOUR) Score, which has been recently validated. The FOUR Score has 4 components with "4" as a maximal score for each item. The individual components are eye responses (eye opening and eye tracking), motor responses (responses to pain and following simple hand commands), brainstem reflexes (pupil, cornea, and cough reflexes), and respiration (breathing rhythm and respiratory drive in ventilated patients). The FOUR Score is a further improvement on previous scales for classifying and communicating impaired consciousness.