To compare the timing of first hospital antenatal care visit by mothers of Aboriginal and non-Aboriginal infants, and to identify the risk and protective factors associated with timeliness of accessing care, mothers who delivered at Campbelltown hospital between October 2005 and November 2006 were surveyed on the maternity ward. This survey was linked to hospital administrative data. Gestational age at first visit to a hospital-based antenatal clinic was compared for mothers of Aboriginal and non-Aboriginal infants. Risks and protective factors associated with timing of antenatal care were also examined using Cox regression and KaplanMeier survival curves. Data on 1520 deliveries were included in this study. Mothers of Aboriginal infants presented slightly later to hospital-based antenatal clinics than mothers of non-Aboriginal infants (median 15.6 weeks versus 14.0 weeks). This difference did not remain after adjustment for all risk and protective factors. The three significant factors remaining were: maternal smoking; not in paid employment; and residence in a disadvantaged suburb. The results may reflect the complex associations that exist between the clustering of disadvantage among families of Aboriginal infants. A multifaceted approach is required to improve the timeliness of hospital-based antenatal care for the mothers of Aboriginal infants.