Abdominal pain is one of the basic clinical presentations of the hereditary angioedema and danazol is a common medicine which has been used for long years in patients with hereditary angioedema. We present two hereditary angioedema patients with abdominal pain albeit under danazol treatment, whose final diagnoses was colon carcinoma. There are two consequences in this article which shall be insisted on: First; in patients with hereditary angioedema, the differential diagnosis of "abdominal pain" is always important even though hereditary angioedema diagnosis exists. And the second; It can be hardy speculated that long term danazol treatment may cause different malignancies.