The expressed sequence tags, derived from the developing tilapia brain, were established in our laboratory. An unique gene, high mobility group proteins 2 (HMG2), were investigated. HMG2 is a non-histone chromatin protein. HMG2 cloned from tilapia, Oreochromis mossambicus, is a gene with open reading frame 642bps, and deduced as 213 amino acid protein sequence. NCBI Conserved Domain search, the Gene Ontology, NEBcutter restrict enzyme analysis, NCBI blastx, and neighbor phylogenetic tree were used for the bioinformatic analysis. In the present study, the protein expression of HMG2 in the BL21 E.coli system, a prokaryotic system, and purified with 6X His Tag NI-NTA affinity chromatography.