The specificity of immunoglobulin E for different cereal grain proteins was investigated using sera from twenty paedialric patients with asthma and/or eczema. Close correlations were observed between radioallergosorbent test values for grain extracts of wheat, rye and barley, and, to a lesser extent, oats. Of the different wheat flour fractions tested, the globulins and glutenins consistently bound higher levels of IgE than the gliadins and albumins. This is in contrast both with bakers' asthma (an allergy to inhaled flour where the albumins are important allergens) and with coeliac disease (in which gliadin is the most toxic fraction). Partial digestion of the flour proteins largely removed their ability to bind IgE, An analytical technique of identifying allergens after gel isoelectric focusing demonstrated that many different flour proteins were involved.