The chief purpose of this communication is to direct attention to the importance of transient and recurrent auricular fibrillation of a paroxysmal character accurring in apparently healthy hearts, in moderately advanced myocarditis, and in other conditions in which the evidence of heart damage is less evident than in valvular disease. The material on which discussion has been based has been gathered from cases recorded in the literature on the subject, and from eight additional cases observed by me and here presented. Intermittent auricular fibrillation in association with frank valvular disease, having been already adequately described, is not included in the case reports. That transient form associated with auricular flutter is also excluded. Intermittent auricular fibrillation first appeared in medical literature in 1907 in a report by Cushny and Edmunds.1They studied a single patient who had been subject to paroxysms of tachycardia with absolute irregularity over a period of