This study attempts to determine if atopy predisposes to, or affects the severity of, bee sting allergy. 119 consecutive patients with definite systemic reactions to Hymenoptera stings and 119 matched controls without a history of Hymenoptera allergy were interviewed and evaluated. These patients with a definite systemic reaction to Hymenoptera had a mean age of 27 years with an age range of 2-73 years; 38% (forty-five out of 119) were 12 years of age or younger. The frequency of atopy (asthma/allergic rhinitis) was 25% (thirty out of 119), and resembles that found in a general population. In the eighty-nine patients (75%) without a personal history of atopy, only 8% had positive scratch tests to pollens, danders or molds, 44% had a positive family history of atopy and a majority had normal serum total IgE levels. Results of the RAST for specific IgE to venoms of honey bee, yellow jacket, hornet, wasp and to phospholipase A were obtained. Patients with asthma had a significantly more severe reaction to their Hymenoptera sting than non-atopic patients, 65%vs 38%, with P <0.05. The severity of sting reaction in those patients with allergic rhinitis without asthma resembled that of the non-atopic patients. Although atopy does not appear to predispose patients to Hymenoptera allergy, asthmatics’Who also have Hymenoptera allergy do have a significantly more severe reaction to a bee sting.