Hereditary angioedema (HAE) caused by a deficiency of C1 esterase inhibitor enzyme (C1-INH) is a very rare, autosomal dominantly inherited genetic disorder, characterized by recurrent peripheral angioedema, painful abdominal attacks and episodes of laryngeal edema. Abdominal attacks are frequent symptoms in adult HAE patients, occurring in more than 90% of the cases. Angioedema in the bowel or abdomen can occur in the absence of cutaneous manifestations and may be easily misdiagnosed unless the clinician has a high degree of awareness to include HAE in the differential diagnosis. Misdiagnosis is associated with inadequate treatments, including unnecessary surgical procedures. Any patient who presents recurrent episodes of swelling should be evaluated for HAE caused by C1-INH deficiency. New therapies could save lives and dramatically improve their quality of life.