This report describes the investigation and public health response to a large point-source outbreak of salmonellosis in Sydney, Australia. The case-series investigation involved telephone interviews with 283 cases or their guardians and active surveillance through hospitals, general practitioners, laboratories and the public health network. In this outbreak 319 cases of gastroenteritis were identified, of which 221 cases (69%) presented to a hospital emergency department and 136 (43%) required hospital admission. This outbreak was unique in its scale and severity and the surge capacity of hospital emergency departments was stretched. It highlights that foodborne illness outbreaks can cause substantial preventable morbidity and resultant health service burden, requiring close attention to regulatory and non-regulatory interventions.