Summary Auricular fibrillation of the fleeting type occurring in an infant with signsof congenital heart disease was followed from the age of 2 months to its fatal termination seven months later. Digitalis was only partially effective in controlling the ventricular rate. Auricular fibrillation in the newborn infant is rare, only one other instance having been reported in the literature. This case differed from ours in that the fibrillation was continuous and was controlled by digitalis.