As part of the Bacillus subtilis genome sequencing project, we have determined the complete nucleotide sequence of a skin element which is located between spoIVCB and spoIIIC. The entire sequence of this element is 48,032 bp in length, and contains 57 ORFs with putative ribosome-binding sites. Two of them correspond to previously sequenced and characterized genes, cwIA and spoIVCA. Furthermore, seven ORF products identified in this element show interesting similarities with known proteins present in data banks, including the phi 105 immunity repressor, the phi 105 Cro-like protein and the SPP1 terminase. These results indicate the possibility that the skin element is a cryptic remnant of an ancestral temperate phage.