Introduction The purpose of this report is to draw attention to a unique disease of cerebral white matter which has been encountered with great frequency among infants who died at the Children's Hospital Medical Center, Boston. Despite the remarkably high incidence of periventricular leukomalacia, which is the name that has been chosen for this pathological entity, it has been the subject of relatively little investigation, particularly in respect to the importance of prenatal and neonatal factors in its production and in respect to the clinical manifestations and to the nature of the pathological changes. Historical Review In 1843, in a lecture concerning the deformities of the human frame, W. J. Little1described universal spasmodic contractures of the limbs which he attributed to abnormal factors in the perinatal period. He emphasized that the majority of these infants were born prematurely and had suffered some form of asphyxia at birth and