This article reviews scientific literature data of the last decade and analyses the possibilities to evaluate functional brain state in comatose children. Observations after the development of coma, its short-term and long-term outcomes show that when duration of coma is over 30 days, the chances to regain consciousness and autonomy are decreased. Coma of hypoxic origin has more complicated course, and its prognosis is worse compared to the one of a traumatic origin. Vegetative condition is observed more frequently as a consequence of hypoxic brain damage. Survival in vegetative condition without recovery of consciousness raises medical, psychological, social, and patient care problems. The article reviews different methodical approaches for the evaluation of functional brain state. Various methods of brain bioelectric evaluation are analyzed, including routine and qualitative methods of electroencephalography, possibilities of its spectral analysis and evoked potentials of various types. The results of the observation that evaluate the changes of brain structure and neurophysiological parameters are reviewed. The analysis of 48 articles draws a conclusion that the most objective criteria for evaluation the prognosis of coma can be achieved while following the clinical condition of the patient in parallel with the brain neuroimaging studies and evaluation of neurophysiological parameters, such as electroencephalography spectral analysis and evoked potentials of brainstem and cortex. The best evaluation of the functional brain state and prognosis of coma can be achieved with repeatable investigations during coma development and comparison of the results of several parameters.