A gene sequence encoding the neuropeptide adipokinetic hormone (AKH) was isolated from a genomic library of the tobacco hornworm, Manduca sexta. 2.5 x 10(5) recombinant plaques were screened with a 29-mer oligonucleotide substituted with deoxyinosine at six ambiguous codon positions. One clone was obtained from which we deduced an intronless gene encoding the AKH precursor (prepro-AKH). From NH2 to COOH terminus, prepro-AKH consists of a signal peptide, a single AKH peptide block followed by a Gly-Lys-Arg processing site, and a 34-residue sequence that appears unrelated to known peptides. The cloned AKH gene sequence hybridized to one transcript from the adult corpus cardiacum/corpus allatum complex. The Manduca genome appears to contain one copy of the AKH gene. These studies are a basis for explaining synthesis of a representative from a widespread, physiologically important family of arthropod neuropeptides.