Sixty-four infants and children showing signs of decerebrate rigidity admitted to a paediatric unit have been studied. Cases of head injury, myelomeningocoele, and tumours were excluded from the series. The aetiological factors causing decerebration in the remainder fell into four main groups: infections, hypoxia, metabolic disease, and intracranial haemorrhage. Increased intracranial pressure was diagnosed in 87%. Defects in homeostasis occurred in 75%, respiratory abnormalities were present in 66%, cardiovascular in 33%, hypothermia in 30%, and hyponatraemia in 17%. Early recognition and treatment of raised intracranial pressure and defects in homeostasis are of the utmost importance if morbidity and mortality are to be minimized. There was a 31% mortality from the acute illness: 30% of the survivors were normal at follow-up examination; the remainder showed varying degrees of handicap. The severity of decerebration showed no correlation with aetiology or prognosis. The study shows that a wide range of disorders can lead to the clinical picture of decerebration in the young child, and that the prognosis is probably much better than in adults showing the same symptoms and signs.