The conclusions deduced from a study of the symptoms of laryngeal diphtheria, as stated in this paper, are the result of personal observations at the bedside. My sole object in presenting them to the distinguished members of this Section is to elicit their candid criticisms, that, profiting by their large experience, I may be the better qualified to decide when to act, when to defer and when to desist. When called into the presence of a little patient suffering from laryngeal diphtheria, the decision of the question whether to intubate or not is a very grave one, and we can only rightly measure our responsibility when we realize that a human life may be sacrificed by an erroneous decision. Aside from the symptoms, our decision will be modified by two circumstances, namely: the previous treatment and the environment of the patient. Before the discovery of antitoxin, the majority of cases