A recombinant DNA clone containing the corazonin gene was isolated from a genomic library of Drosophila melanogaster. Its nucleotide sequence predicts a preprocorazonin consisting of an 19 amino acid putative signal peptide, the 11 amino acid corazonin sequence, a Gly used for amidation, a Lys-Arg proteolytic processing site, and a 39 amino acid corazonin-precursor-related peptide (CPRP). CPRP has an internal Arg-Arg sequence and thus could possibly be further processed into a tripeptide and a 34-mer. Neither CPRP or its possible products are structurally related to any known neuropeptide, and their physiological function is unknown. The structure of the predicted preprocorazonin is remarkably similar to the preprohormone of adipokinetic hormone, which suggests that corazonin and adipokinetic hormone have a common evolutionary origin.