Teasdale and Jennett first presented the Glasgow Coma Scale in 1974 as an aid in the clinical assessment of unconsciousness. It was devised as a formal scheme to overcome the ambiguities and misunderstandings that arose when information about comatose patients was presented and groups of patients were compared. Since then, the Glasgow Coma Scale has been used extensively, being used to grade individual patients, compare effectiveness of treatments, and as a prognostic indicator. It has been incorporated into numerous trauma and critical illness classification systems. However, a number of competing scales have been developed to overcome its perceived deficiencies. These scales are generally more complex. One of the expressed reservations regarding the Glasgow Coma Scale has been its failure to incorporate brainstem reflexes. The scale also includes a numerical skew toward the motor response. An important current issue is the appropriate application of the Glasgow Coma Scale to intubated patients. A number of approaches have been used to assign the verbal score to such patients. The timing of initial scoring is another area of discussion. Despite its drawbacks, the Glasgow Coma Scale remains the most universally utilized level of consciousness scale worldwide. It seems destined to be used in emergency medicine for some time.