A novel stationary phase-response protein has been identified in the acid-soluble protein extract of the thermophilic archaeon, Thermococcus zilligii. N-Terminal sequencing data were used to identify likely genes for homologues of the protein in the complete genome sequences of various archaeal species. The corresponding genes were identified and analysed. The genes encode a protein ranging from 83 to 92 amino acids in length, with a calculated pI ranging from 4.6 to 9.7. The amino acid sequences of the genes were highly conserved, even between members belonging to the different archaeal kingdoms. The computed secondary structure of the protein indicates it consists of four large helical regions separated by short coiled regions. We propose this protein as a candidate regulator of gene expression in stationary phase.