Most patients who have hereditary angioedema receive treatment with androgens or impeded androgens. epsilon-Aminocaproic acid (EACA) is another treatment for C1 inhibitor deficiency. In two patients with angioedema and attacks of abdominal pain due to C1 inhibitor deficiency, long-term treatment with EACA (for more than 2 decades in one of them) was associated with a substantial decrease in the frequency and severity of episodes. One patient had definite hereditary angioedema, and the other had probable hereditary angioedema but the family history was negative for the disease. The EACA therapy caused no major side effects.