Of 161 girls with neonatal encephalopathy who were prospectively assessed until 8 years of age, 7 (4.3%) demonstrated variable degrees of early sexual maturation. This finding was significantly greater than the accepted 0.6%, estimated for the general population. Four of the 7 girls with early sexual maturation had physical disabilities (i.e., 3 with cerebral palsy, 1 neurosensory deafness) which indicated that 10% of the 40 physically disabled girls had early sexual maturation. Three (2.5%) of 121 girls without physical disabilities matured early. Sexual maturation began 5 years or longer after the diagnosis of neonatal encephalopathy. An increased incidence of early sexual maturation in girls with neonatal encephalopathy indicates the importance of long-term follow-up of this population. This study provides an indication of a link between newborn illnesses causing neonatal encephalopathy and early sexual maturation in girls without progressive, structural, intracranial pathology and suggests further study of some girls previously diagnosed as having idiopathic precocious puberty.