Intestinal angioedema caused by angiotensin-converting enzyme inhibitors such as lisinopril is rare but well documented in the literature. Patients with this condition typically present with common symptoms such as diffuse abdominal pain, cramping, nausea, and emesis. Imaging is needed to reveal segmental edema of the small intestine, often associated with free fluid in the abdomen. The authors report 2 cases of intestinal angioedema caused by angiotensin-converting enzyme inhibitors. Awareness of this allergic reaction and careful history taking--noting temporal relationship to occurrence of symptoms--are essential to diagnose this condition; laboratory and radiologic findings are needed to confirm the diagnosis. An accurate diagnosis helps the patient recover quickly and avoid complications from unnecessary tests and invasive procedures.