ObjectiveThis paper analyses the optimal utilization of maternal health services in Indonesia from 2015 to 2018.DesignNational cross-sectional study.SettingThis study takes place in 34 provinces in Indonesia.ParticipantsThe population in this study were mothers in all household members in Basic Health Research of Riskesdas 2018. The sample was all mothers who had a live birth within 5 years before data collection (1 January 2013 to July 2018) and had complete data. The number of samples analysed was 70 878.Primary outcomeWe developed a scoring for the optimal utilization of maternal health services as the outcome variable.ResultsThis analysis involved 70 787 mothers. The utilization of maternal care was not optimal. Mothers who delivered in health facilities achieved 83.3% of services. Better care is experienced more by mothers who live in urban areas. Mothers who delivered at health facilities significantly used threefold optimal care (ORa=3.15; 95% CI 3.00 to 3.30; p<0001). A statistically significant difference of optimal maternal care was found in mothers with better education (ORa=1.22; 95% CI 1.18 to 1.27; p=0.001); holding health insurance (ORa=1.25; 95% CI 1.21 to 1.30; p<0001), having more access to health facilities (ORa=1.13; 95% CI 1.09 to 1.17); p<0.001), less parity (ORa=1.16; 95% CI 1.11 to 1.20; p<0.001).ConclusionThe optimal utilization of MHS is independent of the free services delivery, but having health insurance and less parity brought about a better optimal score for MHS. Mothers in rural areas were more protective of optimal utilization. Finally, the eastern region used more optimal health services.