Peptidoglycan from Deinococcus radiodurans was analyzed by high-performance liquid chromatography and mass spectrometry. The monomeric subunit was: N-acetylglucosamine-N-acetylmuramic acid-L-Ala-D-Glu-(gamma)-L-Orn-[(delta)Gly-Gly]-D-Ala-D-Ala. Cross-linkage was mediated by (Gly)2 bridges, and glycan strands were terminated in (1-->6)anhydro-muramic acid residues. Structural relations with the phylogenetically close Thermus thermophilus are discussed.