Despite the good health status of women and children in Oman, there are still some gaps to be filled. This study explored the adequacy of antenatal care (ANC) utilization of Omani ever-married women and the sociodemographic and health service determinants of adequate and sufficient ANC. In a secondary analysis of a national dataset (N = 1852 women), the percentages of women who had 4+ ANC visits, attended ANC in the 1st trimester and received care by trained personnel were 96.8%, 74.9% and 99.1% respectively. Overall adequacy of ANC (use and sufficiency of recommended basic services) for the surveyed women was 53.8%. After adjustment of other covariates, being pregnant with the 1st baby was the only significant predictor of overall adequacy of ANC (OR 2.2; 95% CI 1.6–3.2). Greater awareness of the need for adequate ANC is required for mothers with more than one baby.