The prevalence of non-hereditary angioedema was investigated in a general population sample (n¿=¿7,931) and in a sample of Danish patients (n¿=¿7,433) tested for deficiency of functional complement C1 esterase inhibitor protein (functional C1 INH). The general population sample (44% response rate) reported a lifetime prevalence of 7.4% for angioedema. In both groups symptoms were most frequent in the lips, head, neck, eyes and tongue. In the C1 INH test normal group angioedema was still active at the time of the study in 53% of the patients, and 36% reported symptoms in the throat, 23% in the abdominal area, 17% had diarrhoea, 11% had vomiting and 6% fainted during attacks. Non-hereditary angioedema has high lifetime prevalence and becomes chronic in approximately 50% of affected patients. Symptoms in the larynx and throat, as well as non-specific symptoms, such as dizziness and abdominal pain, were more frequent than previously reported.