A questionnaire was used from 1972-1978 for 330 consecutive patients with recurrent urticaria of 3 months to 40 years duration. Fifty men and fifty women had only urticaria. The rest had both urticaria and angio-oedema and most of them were women between 24 and 38 years of age. Urticarial attacks were less frequent during the daytime. A personal history of rhinitis, asthma or atopic dermatitis was recorded in more than one-third. Nasal polyps, migraine and arthralgia were found in 6-7% of the patients. Severe psychiatric problems were mentioned by 16%. Abdominal problems, mainly gastritis, were described by 44%. A history of side effects from drugs was found in 32% of the patients. Food was mentioned as a factor worsening the weals by 30% and drinks by 18%. Fruits, vegetables and nuts were the most common. Despite all cases with physical urticaria having been excluded, physical factors such as exercise were considered by 20% to make the urticaria worse. Provocation tests with various food additives such as azo dyes, benzoates, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA) sorbic acid, quinoline yellow, carotene, canthaxanthine, annatto and nitrite revealed one or more positive reactions in one-third of the patients, one-third showed negative provocation tests and, in the rest, one or several tests were questionable. Routine history of other diseases. The fibrin microclot generation test which test which indicates the presence of circulating endotoxins was positive in 24%.