Neonatal abstinence syndrome (NAS) occurs after in utero exposure to opioids, but outcomes after the postnatal period are unclear. Our objectives were to characterize childhood hospitalization after NAS.Population-based linkage study of births, hospitalization, and death records of all children registered in New South Wales (NSW), Australia, between 2000 and 2011 to a maximum of 13 years. Infants with an International Statistical Classification of Disease and Related Problems, 10th Edition, Australian Modification, coding of NAS (P96.1, n = 3842) were compared with 1,018,421 live born infants without an NAS diagnosis.Infants with NAS were more likely to be admitted into a nursery (odds ratio 15.6, 95% confidence interval: 14.5-16.8) and be hospitalized longer (10.0 vs 3.0 days). In childhood, they were more likely to be rehospitalized (1.6, 1.5-1.7), die during hospitalization (3.3, 2.1-5.1), and be hospitalized for assaults (15.2, 11.3-20.6), maltreatment (21.0, 14.3-30.9), poisoning (3.6, 2.6-4.8), and mental/behavioral (2.6, 2.1-3.2) and visual (2.9, 2.5-3.5) disorders. Mothers of infants with NAS were more likely to be Indigenous (6.4, 6.0-7.0), have no antenatal care (6.6, 5.9-7.4), and be socioeconomically deprived (1.6, 1.5-1.7). Regression analyses demonstrated that NAS was the most important predictor of admissions for maltreatment (odds ratio 4.5, 95% confidence interval: 3.4-6.1) and mental and behavioral disorders (2.3, 1.9-2.9), even after accounting for prematurity, maternal age, and Indigenous status.Children with NAS are more likely to be rehospitalized during childhood for maltreatment, trauma, and mental and behavioral disorders even after accounting for prematurity. This continues to adolescence and emphasizes the critical need for continued support of this vulnerable group after resolution of NAS.