Patients with hereditary angioedema have episodes of local swelling, usually affecting the face, extremities, upper airway, and gastrointestinal tract. Only infrequently does it cause recurrent abdominal pain (with or without ascites); however, because it has potentially life-threatening complications, an early diagnosis is important. We describe a case of type I hereditary angioedema (a quantitative deficit of C1 inhibitor), the sole initial symptom of which was severe recurrent and self-limited abdominal pain, accompanied by ascites during these episodes. During a 4-yr period of treatment with danazol, the patient was virtually asymptomatic, despite levels of C4 and C1 inhibitor that remained below normal limits, and there have been no major side effects that could be attributed to treatment with androgens.