CONCLUSIONS Specific immunoglobulin E (IgE) reactivity towards the major mugwort allergen Art v 1 is a good indicator for Art v sensitization. Allergens from the ragweed species Amb t and Amb a possibly share common IgE-binding epitopes. OBJECTIVE The aim of this study was to investigate the reactivity pattern of IgE in Chinese patients with weed pollen-induced allergic rhinitis. METHODS Sera from 50 weed pollen-induced allergic rhinitis patients were tested for specific serum IgE reactivity against allergenic extracts of mugwort (Artemisia vulgaris, Art v), short ragweed (Ambrosia artemisiifolia, Amb a), giant ragweed (Ambrosia trifida, Amb t), and single allergens of Art v 1, Art v 3, Amb a 1, and profilin. RESULTS Sera from 88% of the patients demonstrated positive specific IgE reactivity to Art v, and of these 82% were positive to Art v 1. Sera from 38% of the patients showed positive specific IgE reactivity to both ragweed species Amb t and Amb a. A strong correlation was found between the specific IgE levels of Amb t and Amb a. Of the Amb a IgE-positive patients, 38% were positive for Amb a 1. Of all patient sera tested, 12% were specific IgE-positive to profilin.