Abstract: Juvenile hormone acid methyltransferase gene was cloned using a cDNA derived from the corpora allata of Bombyx mori by differential display methods. A recombinant protein expressed in Escherichia coli, which was transformed with a vector DNA incorporating the gene, was found to have juvenile hormone acid methyltransferase activity. Based on amino acid sequence homology, juvenile hormone acid methyltransferase genes were found from Drosophila melanogaster, Anopheles gambiae, Spodoptera litura, and Helicoverpa armigera. The proteins encoded by the juvenile hormone acid methyltransferase genes derived from Drosophila melanogaster, Spodoptera litura, and Helicoverpa armigera were found to have juvenile hormone acid methyltransferase activities.