BACKGROUND: Immigration is increasingly common worldwide and its impact on neonatal intensive care unit outcomes is uncertain. AIMS: To determine the outcomes of children of immigrant mothers admitted to NICUs in New South Wales (NSW), Australia, between 2000 and 2006. STUDY DESIGN: Record linkage study of routinely collected state-based health databases. SUBJECTS: Infants of Australian-born (9813, 81.9%) and overseas born mothers (2166, 18.1%). OUTCOME MEASURES: NICU and childhood outcomes to a maximum 5 years of age. RESULTS: Immigrant mothers came from 122 countries, 897 (44%) from high income regions. Australian born mothers were more likely to be teenaged (Odds Ratio, 95% confidence interval: 3.07, 2.21-4.26), use drugs (3.55, 2.49-5.06) and suffer an antepartum hemorrhage (1.29, 1.14-1.48). They were less likely to have gestational diabetes (0.45, 0.38-0.54), fetal distress (0.75, 0.66-0.85) and intrauterine growth restriction (0.80, 0.67-0.93). Their infants were more likely to be admitted to the NICU for prematurity but less likely to have low 5 min Apgar scores (0.81, 0.69-0.93) or a congenital abnormality (0.79, 0.70-0.90). Infants of Middle-Eastern mothers had the lowest hospital survival rate (88.5%). Children of immigrant Asian mothers were least likely to be rehospitalized after NICU discharge (1.66, 1.27-2.17). CONCLUSIONS: NICU outcomes are affected by maternal country of birth even within the same ethnic group. Further study regarding the impact of paternal race and immigration status and duration of residency will provide data for the changing cultural environment of global perinatal care.