Coma is the disorder of consciousness because of the damage to diffused bilateral cerebral hemisphere cortex or reticular activating system. Coma can be caused by neurogenic (head brain injury), metabolic (endogenic), and toxic (exogenic) factors. To determine the cause of metabolic and toxic coma, laboratory tests are performed; in case of neurogenic coma, the neurologic examination is essential, when five systems are evaluated: the level of consciousness (according to Glasgow Coma Scale or Full Outline of Unresponsiveness Scale), photoreaction of pupils and ophthalmoscopic examination, oculomotoric, motoric, and cardiopulmonary systems. For the treatment of coma, adequate oxygenation and correction of blood circulation disorders are important. The treatment of metabolic coma is guided by special schemes; antidotes often are needed in the treatment of toxic coma, and surgery helps if traumatic brain injury is present. The prognosis and outcomes of the comatose patient depend on the age and comorbid diseases of the patient, the underlying cause of coma, timely medical help and its quality, and intensive treatment and care of the patient in coma.