The classification of a patient as terminally ill is based on an expert diagnosis of a severe and irreversible disease and the absence of an effective available treatment, according to present medical knowledge. Terminal diseases must not be confused with severe ones, since the latter may be reversible with an adequate and timely treatment. The physician assumes a great responsibility at the moment of diagnosing a patient as terminally ill. The professional must assume his care until the moment of death. This care must be oriented to the alleviation of symptoms and to provide the best possible quality of life. Also, help must be provided to deal with personal, legal and religious issues that may concern the patient. (Rev Méd Chile 2000; 128: 547-52).