A 14 years old boy experienced an anaphylactic reaction of dyspnea, vomiting, urticaria and hypotension after he ate sunflower seeds. Specific IgE-mediated hypersensitivity to sunflower seen extract was demonstrated by skin tests and radioallergosorbent test (RAST). By immunoblotting test analysis (SDS-PAGE, Western blotting method), the allergenic activity of sunflower seem were shown to be in the MW range of 13.5 Kd.