Background: Few studies have evaluated IgE-mediated hypersensitivity to melon with details of clinical reactions confirmed by double-blind, placebo-controlled, food challenges (DBPCFCs). Objective: We sought to investigate clinical features (type and severity of reactions, age at onset, results of skin prick and in vitro tests, and incidence of other allergic diseases and associated food allergies) of acute allergic reactions to melon confirmed by DBPCFCs. Methods: Fifty-three consecutive adult patients complaining of adverse reactions to melon were included in the study. Skin prick tests and detection of specific IgE were performed in all patients with melon, avocado, kiwi, banana, chestnut, latex, pollen, and other offending foods. Patients first underwent an open food challenge, unless they had a convincing history of severe anaphylaxis. Positive open food challenge reactions were subsequently evaluated by DBPCFCs. Results: Actual clinical reactivity was confirmed in 19 (36%) of 53 patients. The most frequent symptom was oral allergy syndrome (n = 14), but two patients experienced life-threatening reactions, including respiratory symptoms and hypotension. The positive predictive value for a skin prick test was 42%, and that for specific IgE measurement was 44%. Forty-five reactions to 15 other foods were confirmed in 18 patients. The most common foods associated with melon allergy were avocado (n = 7), banana (n = 7), kiwi (n = 6), watermelon (n = 6), and peach (n = 5). Onset of melon-induced allergic symptoms occurred from 6 to 45 years (median, 20 years), preceded by seasonal rhinitis, asthma, or both in 88% (15/17). Conclusion: About one third of reported reactions to melon are confirmed by means of DBPCFC, which has been proven to be the most reliable procedure in the diagnosis of clinical fruit allergy. Isolated melon allergy is rare, with most patients either having allergic rhinitis, asthma, or both and associated food allergies. (J Allergy Clin Immunol 2000;106:968-72.)