We report a case of a 12-week-old previously normal infant with severe brain damage after an episode of asphyxia during an RS-virus infection. Sub-acute MRI was normal, but new functional techniques, PET (positron emission tomography) and MRS (magnetic resonance spectroscopy) were severely abnormal. At an outpatient clinic three months later, he had developed microencephaly and the MRI was now severely abnormal. The case shows the importance of using multimodality functional imaging techniques to assess the cerebral status of infants for prognosis and course of treatment.