Sneezing, flush, headache, diarrhea, skin itch, and shortness of breath are symptoms occurring in patients intolerant to wine after drinking one glass of red wine. The role of histamine in wine intolerance was evaluated by a red wine provocation test in 28 patients with a history of wine intolerance and in 10 controls with good tolerance of wine. Patients were challenged with 125 ml red wine (equivalent to 50 micrograms histamine); blood samples were drawn before and after 15 and 30 minutes. Plasma histamine was assessed by a radioimmunoassay. Lung function tests were performed before and after the wine test. Twenty-two of twenty-eight patients had symptoms showing significantly higher plasma histamine levels 30 minutes after wine challenge (p < .01) compared with asymptomatic controls. Basal histamine levels of patients were higher (p < .05) than in controls. A slight asthmatic attack as well as a 30% decrease of FEF 25 was seen in 2/22 patients. Terfenadine premedication significantly eliminated symptoms in 10/12 patients (p < .05) in a subsequent wine test. Histamine assessment was done in 52 wines (red, white, and champagne) and in 17 beers by radioimmunoassay. Histamine levels ranged from 3-120 micrograms/l in white wines; 15-670 micrograms/l in champagnes; 60-3800 micrograms/l in red wines; and 21-305 micrograms/l in beers. Histamine is causing wine intolerance. Patients intolerant to wine seem to have diminished histamine degradation probably based on a deficiency of diamine oxidase.