Reasons for performing study: Research into risk factors specific for fatality in flat racing should be focused at a regional level as the risk factors may differ among countries and even regions within countries. Objective: To identify risk factors for fatality of Thoroughbred racehorses in flat starts on all racecourses in Victoria, Australia between 1989 and 2004. Methods: Fatalities comprised all horses that died during or immediately after a flat race or official flat trial, and all horses that were subjected to euthanasia within 24 h of an event in which an injury was sustained. The retrospective study involved 283 case starts and 3307 control starts. Univariable and multivariable backward stepwise logistic regression was used to identify risk factors for fatality at any one start. Results: In the final multivariable model, horse gender, prior racing history, race length, racing year, racecourse location and track rating were associated with fatality. Conclusions: This study identified specific risk factors for fatality. The findings are consistent with the hypothesis that horses accumulating high speed exercise are predisposed to catastrophic injury. The study has also highlighted the need to investigate further the adverse effects of different track ratings on the incidence of injury and subsequent fatality. Relevance: The results will facilitate the development of effective strategies to improve overall safety of horses and jockeys in flat racing in Victoria, Australia.