Objectives: To establish how frequently supervision was explicitly identified as a factor in coroner-certified unintentional drowning deaths of children in Australia, and to determine the percentage of cases where failure of supervision may have been a contributing factor; also, to identify the proportion of cases with coroners' recommendations relating to supervision and unintentional child drownings. Design and setting: Retrospective case-series analysis of unintentional drowning deaths of children (aged 0-14 years) in Australia from 1 July 2000 to 30 June 2009, based on data from the National Coroners Information System (NCIS). Main outcome measures: Number of unintentional child drownings and the extent to which supervisory factors were formally reported by coroners as a contributing factor; proportion of cases with coroners' findings that also had coroners' recommendations. Results: 339 relevant child drownings were identified within the 9-year period. Supervision (or lack thereof) was identified as a contributing factor in 71.7%. However, specific detail about the nature and extent of supervision varied across these cases. The availability of text documents describing the findings (police reports, coroners' findings, autopsy reports, toxicology reports), and the level of detail within these documents, also varied considerably across jurisdictions. Despite almost half (47.2%) of the closed cases having coroners' findings attached, only 15% of these also included specific coroners' recommendations. Conclusion: Lack of adequate supervision, or lack thereof, is a significant problem associated with fatal drownings of children in Australia. There is a need to improve the standard and consistency of information contained in text documents within the NCIS to provide more useful information for preventing child drowning deaths.