Abstract
Respiratory viruses and histological appearances of the lung were studied prospectively in an unselected series of 104 children who died between 1 week and 2 years of age. Thirty-one of the cases were cot deaths. Seven of these showed evidence of active virus infection in the lower respiratory tract. Similar evidence was found in two children who died from known causes and did not have a severe respiratory illness terminally. Although in some cases of cot death respiratory viruses may be responsible for a severe and rapidly overwhelming illness, the present results are compatible with an alternative hypothesis-namely, that minor respiratory illness may trigger sudden apnoea.