Hemolytic uremic syndrome (HUS) is associated with consumption of under cooked gound beef, characterized by triad of renal failure, microangiopathic hemolytic anemia and thrombocytopenia. Early recognition of this disease, maintenance of fluid balance and proper dialysis seems to prevent acute mortality. A 23-month-old boy was admitted with abdominal pain, bloody diarrhea and fever. On hospital day (HD) #2, he developed aggravated abdominal pain compared to the initial assessment. Contrast abdominal computed tomography demonstrated findings suggestive acute appendicitis so the patient was underwent laparoscopic appendectomy. On HD #3 and #4, his laboratory findings showed marked thrombocytopenia and serum creatinine elevation. He was transferred to another hospital for dialysis with the impression of acute renal failure. Later, verotoxin-producing Escherichia coli, which is one of the most common causes of HUS, was detected on his initial stool examination. HUS can present with prodromal gastrointestinal symptoms mimicking acute abdomen. So even if the patient is primarily diagnosed acute abdomen in the initial setting, clinicians should always keep in mind of other fatal conditions disease, such as HUS. To our knowledge, this is the first case report of acute appendicitis followed by HUS in South Korea.