Genes for URF3, tRNAala, tRNAarg, tRNAasn, tRNASer, tRNA1u, tRNAphe, and the carboxyl terminal segment of the URF5 gene have een identified within a sequenced segment of the mtDNA molecule of Drosophila yakuba. The genes occur in the order given. The URF5 and tRNAPhe genes are transcribed in the same direction as replication while the URF3 and remaining five tRNA genes are transcribed in the opposite direction. Considerable differences exist in the relative arrangement of these genes in D. yakuba and mammalian mtDNA molecules. In the tRNAser gene an eleven nucleotide loop, within which secondary structure formation seems unlikely, replaces the dihydrouridine am, and both the variable loop (six nucleotides) and the TPC loop (nine nucleotides) are larger than in any other D. yakuba tRNA gene. As available evidence is consistent with AGA codons specifying serine rather than arginine in the Drosophila mitochondrial genetic code, the possibility is considered that the 5GU anticodon of the D. yakuba tRNAser gene can recognize AGA as well as AGY codons.