A 20,115-nt region of the Mycoplasma gallisepticum A5959 genome was sequenced (GenBank accession no. AF036708). The region contains the rrn23-5 and S10 operons, the lactate dehydrogenase gene, and two open reading frames (ORF293 and ORF129/ORF171) coding for proteins of unknown function. The rrn23-5 operon includes genes for 23S and 5S rRNAs. The S10 operon includes genes for 20 ribosomal proteins, SecY transport protein, adenylate kinase, and methionine aminopeptidase, and lacks the infA-rpl36-rps13-rpoA-rpl17 genes found in the S10 operon of M. genitalium, M. pneumoniae, and Bacillus subtilis. The product of M gallisepticum ldh is equally similar to the corresponding proteins of mycoplasmata and B. subtilis but contains only a part of the motif characteristic of the active center of lactate dehydrogenases. The chromosome region adjacent to the sequenced one contains uvrA, nrdE, nrdF, and ptsI.