Shiga toxin-producing Escherichia coli (STEC) infections are an important cause of foodborne disease in Australia. Three percent to 7% of sporadic patients develop hemolytic uremic syndrome (HUS) and 40% of patients with HUS develop chronic complications. To examine costs associated with illness, we interviewed patients notified to the South Australian Department of Health with a structured questionnaire regarding severity of illness, medical treatment, time lost from work, hospitalization, and other costs. In 2003-2006, we interviewed 46 patients of STEC infection, 2 of whom developed HUS. The median duration of illness was 7 days (range 3-31 days) and 41% (19/46) of patients were admitted to hospital. The estimated total cost for the 46 STEC cases in South Australia was AUD$144,087, equating to a mean cost of AUD$3132 per case. We estimate that the annual total costs of STEC infection in South Australia and Australia are AUD$200,283 and AUD$2,633,181, respectively. We used linear regression to identify that STEC infection costs increase by AUD$608 per day regardless of severity, and that more severe illness is strong predictor of cost. This is the first Australian study to examine costs of STEC infection and highlights the significant impact of this illness.