Abstract Recombinant cloned genomic DNA fragments homologous to cultured muscle cell cDNA from Drosophila melanogaster have been isolated and partially characterized. Each of the eight analyzed clones has been shown by hybrid-selected translation and polyacrylamide gel electrophoresis to encode at least one polypeptide. Three clones hybrid-select two proteins. The developmental pattern of expression of each clone has been determined by hybridization of mRNA isolated from staged embryos, myogenic cultures, and Schneider cells to EcoRI digestion fragments of the cloned DNA. The pattern of hybridization shows that some EcoRI fragments hybridize to transcripts that are developmentally regulated during embryogenesis and in muscle cell cultures as well as transcripts that are always expressed. Each clone has been mapped by in situ hybridization and shown to hybridize to a different single chromosomal locus on salivary gland polytene chromosomes. One clone hybridized to a single chromosomal locus and to the chromocenter.