Background. An increasing proportion of births in Taiwan are to immigrant women (13% in 2006), who are, on average socio-economically disadvantaged relative to native-born Taiwanese women and are married to lower socioeconomic status Taiwanese men. Some countries have experienced an epidemiological paradox of better immigrant birth outcomes relative to native-born populations despite apparent demographic disadvantages. This study tested for a similar epidemiological paradox in Taiwan. Method. A retrospective, observational hospital-based study was conducted, based on systematic chart review of all singleton, live births during 2002-2007 at a regional hospital in Kaohsiung Taiwan. Data were extracted on maternal demographic and behavioral characteristics (age, height, educational status, national origin, pre-pregnant weight, smoking and alcohol use during pregnancy) paternal age, pregnancy characteristics and obstetric history (net weight gain, prenatal care adequacy, history of cesarean and pregnancy loss, pregnancy complications), and neonatal characteristics (birth weight, gestational age). The key neonatal outcomes of interest are birth weight, and the likelihood of preterm birth and low birth weight. Multiple regression analyses were used to examine differences in outcomes of Vietnamese, Chinese and native-born Taiwanese mothers. Results. Of total 3371 births satisfying the inclusion criteria, 19.0% were to Chinese and Vietnamese mothers. Taiwanese women had the lowest mean neonatal birth weight, and highest rates of low birth weight and preterm delivery among the three groups. Adjusted mean birth weight for Chinese and Vietnamese mothers was 75.2g and 52.1g lower respectively than for Taiwanese (both p<0.01). Chinese and Vietnamese-origin women had lower odds of preterm birth than Taiwanese (OR=0.45 and 0.41, respectively. Conclusion. Adjusted for confounders, Chinese and Vietnamese mothers have better neonatal outcomes, consistent with an epidemiological paradox in immigrant birth outcomes.