Scalds from hot tap water are serious injuries that are potentially preventable by restricting the temperature of hot tap water delivery. In July 1999, regulations were introduced in NSW to require that all new hot water installations deliver water at temperatures not exceeding 50 °C to sanitary fixtures. This study investigates trends in hot tap water scald injury hospitalisations following the introduction of these regulations. Hot tap water scald cases for 1999-2007 were identified from hospitalisation data for all public and private hospitals in NSW. To investigate hot tap water scald hospitalisations over time, negative binomial regression analysis was performed. There were 845 hospitalisations for hot tap water scalds in NSW over the period of the study. Hospital admission rates for hot tap water scalds decreased by an estimated 6% (3.2-8.5, 95%CI) per year since the introduction of regulations. While those most at risk were infants, toddlers and the elderly, almost a third of hospitalisations were for adults (25-64 years). The majority of hot tap water scalds were sustained at home and a further 4% occurred in a residential institute or school. The majority of scalds were severe, and a quarter required admission for longer than a week. The introduction of regulations in NSW appears to have had a positive impact on the rates of hospitalisations for hot tap water scalds; however, scalds continue to cause significant morbidity and mortality. This highlights the need for a review of the scope and implementation of the existing regulations and ongoing education of the general public to the dangers of hot tap water. © 2009 Elsevier Ltd and ISBI.