The DNA fragment identical to the right shoulder of the inverted repeat from the par-region of ColE1 plasmid has been synthesized chemically. It is shown to participate in the plasmid multimers resolution and to define the stable inheritance of the plasmid pKS1 containing the fragment in Escherichia coli C600 cells as well as in the multirecombinogenic strain Escherichia coli JC8679. The efficiency of the fragments functioning in Escherichia coli JC8679 is not enough for resolution of all forms of oligomeric pKS1 DNA. The site for recombinase action is found to be located in the synthesized oligonucleotide. However, some extra sequences of DNA located within the region of inverted repeat are necessary for maximally efficient functioning of the recombinase, the enzyme participating in plasmid multimers resolution.