Acute appendicitis is the one of the most common operative disease in general surgery following by acute cholecystitis and intestinal obstruction, and most of the acute appendicitis is diagnosed at the emergency room.

Especially, because the number of patient who present atypical symptoms of acute appendicitis increases, it is hard to be diagnosed as acute appendicitis and it is often misdiagnosed as other disease.

We report one case of acute appendicitis diagnosed by colonoscopy performed to evaluate for atypical abdominal pain.