A cDNA fragment for an allergen, Cry j 1 in sugi (Cryptomeria japonica D. Don) was generated by the reverse transcriptase-polymerase chain reaction. Using this cDNA fragment, we determined the number of copies of theCry j 1 gene in the sugi genome and the organ-specific expression of theCry j 1 gene in sugi trees. TheCry j 1 genes formed a small multigene family within the sugi genome, with a stoichiometry of approximately five to eight copies of theCry j 1 gene per diploid genome. TheCry j 1 gene was expressed exclusively in male reproductive tissues, particularly in mature pollen.