By searching the current protein sequence databases using sequences from human and chicken histones H1/H5, H2A, H2B, H3 and H4, a database of aligned histone protein sequences with statistically significant sequence similarity to the search sequence was constructed. In addition, a nucleotide sequence database of the corresponding coding regions for these proteins has been assembled. The region of each of the core histones containing the histone fold motif is identified in the protein alignments. The database contains >1300 protein and nucleotide sequences. All sequences and alignments in this database are available through the World Wide Web at http://www.ncbi.nlm.nih.gov/Baxevani/HISTO NES.