The human intestinal tract at birth isfree of bacteria,1 but its status as regards the presence of viruses in the perinatal period is not known. During the first day of life, colonization with "normal" intestinal bacteria occurs, and this is usually not associated with illness.1 The analogous recovery of viruses from the intestinal tract of very young infants who remain well has only recently been reported. Sabin et al. were able to detect ECHO viruses during the first 4 days of life in rectal swabs taken from infants living at home; 7 of 58 infants studied afforded virus recovery.2 Outbreaks of various illnesses in newborn and older infants caused by members of the enterovirus and adenovirus families have been described,3-9 and a few longitudinal surveys describing the distribution of enteroviruses and adenoviruses among healthy institutionalized older infants10,11 and among normal older infants living in the community12-20 have also been reported.