The nucleotide sequence of the xylanase gene (xynS) from alkali-tolerant Bacillus sp. YA.14 was determined and analyzed. A 639 base pairs open reading frame for xynS gene was observed and encoded for a protein of 213 amino acids with a molecular weight of 23, 339. S1 nuclease mapping showed that the transcription initiation site of the xynS gene did not exist in the cloned DNA. Ribosome binding site sequence with the free energy of -18.8 Kcal/mol was observed 8 base pairs upstream from the initiation codon, ATG. The proposed signal sequence consisted of 28 amino acids, of which 3 were basic amino acid residues and 21 were hydrophobic amino acid residues. When the amino acid sequences of xylanases were compared, Bacillus sp. YA-14 xylanase showed 48% homology with Bacillus sp. YC-335 xylanase and 96% homology with xylanases from B. subtilis and B. circulans.