The first results concerning the role of event related potentials (P300) in assessing a prognosis in comatose patients reported in the literature have been encouraging. The cause of the coma is an important prognostic factor by itself, especially when traumatic and anoxic comas are compared, with a less favorable prognosis in anoxic coma. In our study, only anoxic patients have been investigated using somatosensory evoked potentials, brainstem auditory evoked potentials P300 auditory event-related potentials. Clinical evaluation was performed using Glasgow, Liege and Jouvet coma scales. In twenty patients studied, six had a positive P300 and three of them awake. Out of the 14 patients without a P300 only one awoke (5%), 12 patients died and one is in deep coma. Despite the small number of patients in this study, the first results confirm the interest of auditory P300, in addition to clinical evaluation and evoked potential testing.