Objective Stillbirth investigations incur healthcare costs, but these investigations are necessary to provide information that will help reduce the risk of a recurrent stillbirth, as well as advice regarding family planning and future pregnancies. The aims of this study were to determine the healthcare costs of investigations for stillbirths, identify drivers and assess cost differences between explained and unexplained stillbirths. Methods Data from 697 stillbirths were extracted from the Stillbirth Causes Study covering the period 2013-18. The dataset comprised all investigations related to stillbirth on the mother, baby and placenta. Unit costs applied were sourced from the Australian Medicare Benefits Schedule, local hospital estimates and published literature. Multivariable regression analyses were used to assess key factors in cost estimates. Results In all, 200 (28.7%) stillbirths were unexplained and 76.8% of these had between five and eight core investigations. Unexplained stillbirths were twice as likely to have eight core investigations as explained stillbirths (16.5% vs 7.7%). The estimated aggregated cost of stillbirth investigations for 697 stillbirths was A$2.13 million (mean A$3060, median A$4246). The main cost drivers were autopsies or cytogenetic screening. Mean costs were similar when stillbirths had known or unknown causes and by reason for stillbirth among cases with definable causes. Conclusion Investigations for stillbirth in Australia cost approximately A$4200 per stillbirth on average and are critical for managing future pregnancies and preventing more stillbirths. These findings improve our understanding of the costs that may be averted if stillbirths can be prevented through primary prevention initiatives. What is known about the topic? Approximately 2000 stillbirths occur each year in Australia, and this trend has not changed for several decades. Stillbirth investigations incur healthcare costs, but these investigations are necessary to provide information to help reduce the risk of a recurrent stillbirth and advice regarding family planning and future pregnancies. Recommendations for the core set of stillbirth investigations have recently been agreed upon by consensus. What does this paper add? The costs of stillbirth investigations are unknown in Australia. The assessment of these costs is challenging because not all investigations involved in stillbirths are recorded within formal administrative systems because a stillborn baby is not formally recognised as a patient. The present population-based analysis of 697 stillbirths in Australia estimated that, on average, A$4200 was spent on investigations for each stillbirth, with key drivers being autopsies and cytogenetic screening. These costs are typical, with most cases having between five and eight of the core eight recommended investigations. What are the implications for practitioners? There are cost implications for stillbirth investigations, and this analysis gives a true account of current practice in Australia. Together with the high downstream economic costs of stillbirths, the cost burden of stillbirth investigations is high but ultimately avoidable when practitioners adhere to the core investigations, build knowledge around preventable risk factors and use this information to reduce the number of stillbirths.