Brain injury due to hypoxia, trauma, stroke, poisoning, and other pathological conditions may result in chronic disorders of consciousness in the form of vegetative state (VS) or minimally conscious state (MCS). VS is a condition defining patients who have awaken from coma, open eyes spontaneously or on command, but still are not aware of themselves or their environment, showing only a reflex motor responses. MCS is a condition in which patients are not able to communicate consistently, but they are not already in the VS, because of evident signs of awareness of themselves and the environment. The paper discusses the diagnostic criteria, etiology as well as diagnostic procedures and treatment of VS and MCS