An upper respiratory tract infection in a 22-month-old boy was followed by rapid loss of consciousness, hypoglycaemia, uraemia, and death. Necropsy examination showed fatty change of liver and kidneys, severe cerebral oedema, bronchiolitis, and endocardial fibroelastosis affecting the left ventricle. Immunofluorescence staining showed infection with respiratory syncytial virus (RSV). The clinical and pathological findings were those of Reye's syndrome, not previously reported accompanying RSV infection.