The stools of 37 newborn babies born in hospital were examined for the presence of virus. An extract of every stool passed by each baby was examined in the electron microscopy and inoculated into cell cultures. The babies were delivered in four separate maternity units (A-D). All the babies from unit A and C(9 babies) were found to be excreting rotavirus though none showed any evidence of diarrhoea. Two of the babies also excreted astrovirus. Subsequently unit A was closed for cleaning and, on reopening with more restrictions on visitors, a further 19 babies were examined. No virus was found in any of their stools, nor was virus observed in the stools of babies from units B and D, where visiting was also more restricted. Visiting restrictions in these units excluded older siblings of the babies. No virus was cultured from any stools in this study.