The objective of this study is to describe the utilization of prenatal care in American Samoan women and to identify socio-demographic predictors of inadequate prenatal care utilization. Using data from prenatal clinic records, women (n = 692) were categorized according to the adequacy of prenatal care utilization index as having received adequate plus, adequate, intermediate or inadequate prenatal care during their pregnancy. Categorical socio-demographic predictors of the timing of initiation of prenatal care (week of gestation) and the adequacy of received services were identified using one way analysis of variance and independent samples t tests. Between 2001 and 2008 85.4 % of women received inadequate prenatal care. Parity (P = 0.02), maternal unemployment (P = 0.03), and both parents being unemployed (P = 0.03) were negatively associated with the timing of prenatal care initiation. Giving birth in 2007-2008, after a prenatal care incentive scheme had been introduced in the major hospital, was associated with earlier initiation of prenatal care (20.75 vs. 25.12 weeks; P < 0.01) and improved adequacy of received services (95.04 vs. 83.8 %; P = 0.02). The poor prenatal care utilization in American Samoa is a major concern. Improving healthcare accessibility will be key in encouraging women to attend prenatal care. The significant improvements in the adequacy of prenatal care seen in 2007-2008 suggest that the prenatal care incentive program implemented in 2006 may be a very positive step toward addressing issues of prenatal care utilization in this population.