A method for the preparation of a novel recombinant DNA, which comprises (1) cleaving with an endonuclease a temperate phage DNA having an endonuclease-sensitive region not in the DNA segment participating in the replication of phage DNA and the integration of phage DNA into a host chromosome but at least in the DNA segment carrying genetic information for the coat protein production and another DNA carrying intended genetic information, (2) adding DNA-ligase to the mixture of both cleft DNA's, and (3) recovering from the mixture a phage DNA having its coat protein producing ability deleted by the replacement of the DNA segments carrying genetic information for the coat protein production with a DNA fragment carrying the intended information.