Total synthesis of human beta-endorphin gene has been designed for the expression in bacterial system. Eight individual oligonucleotides corresponding to the beta-endorphin gene were chemically synthesized and joined through the enzyme-catalyzed reaction. The final yield of the 111-nucleotide-long synthetic beta-endorphin gene construct was about 10% of the total oligonucleotide used. The synthetic human beta-endorphin gene was cloned into the bacterium Escherichia coli, using pUC8 vector and shown to have the correct nucleotide sequences as designed.