Asians are often considered a single group in epidemiological research. This study examines the extent of differences in maternal risks and birth outcomes for six Asian subgroups. Using linked birth/infant death certificate data from the State of California for the years 1992-97, we assessed maternal socio-economic risks and their effect on birthweight, preterm delivery (PTD), neonatal, post-neonatal and infant mortality for Filipino (87,120), Chinese (67,228), Vietnamese (45,237), Korean (23,431), Cambodian/Laotian (21,239) and Japanese (18,276) live singleton births. The analysis also included information about non-Hispanic whites and non-Hispanic blacks in order to give a sense of the magnitude of risks among Asians. Logistic regression models explored the effect of maternal risk factors and PTD on Asian subgroup differences in neonatal and post-neonatal mortality, using Japanese as the reference group. Across Asian subgroups, the differences ranged from 2.5- to 135-fold for maternal risks, and 2.2-fold for infant mortality rate. PTD was an important contributor to neonatal mortality differences. Maternal risk factors contributed to the disparities in post-neonatal mortality. Significant differences in perinatal health across Asian subgroups deserve ethnicity-specific interventions addressing PTD, teen pregnancy, maternal education, parity and access to prenatal care.