An allergenic protein with Mr of about 16 kDa was isolated from rice salt-soluble fraction based on the reactivity with IgE antibodies from patients allergic to rice. A cDNA clone encoding the 16 kDa allergenic protein (1 GK-allergen) was isolated from a cDNA library of maturing rice seeds, and the deduced amino acid sequence of 16K-allergen showed considerable similarity to wheat and barley a-amylase/trypsin inhibitors, which have recently been identified as major allergens associated with baker's asthma. An antisense RNA strategy was applied to repress the allergen gene expression in maturing rice seeds. Chimerit genes producing antisense RNAs of 16K-allergen under control of some promoters of rice seed specific genes including the 1 GK-allergen gene were introduced into rice with a hygromycin phosphotransferase gene by electroporation, Rice plants were independently regenerated from hygromycin-resistant calli, and their selfed seeds were obtained. Immunoblotting and ELISA analyses of the seeds using a monoclonal antibody to 16K-allergen suggested that allergen content of seeds from several transgenic rice plants was markedly lower than that of the seeds from parental wild type rice.