To investigate the relationship between two tetracycline resistance ($Tc^r$) plasmids, the 24.82-kb pKHl and the 4.44-kb pKH6, of Staphylococcus aureus isolated in Korea, cloning of the 4570-bp HindIII fragment into pBluescript II $KS^+$ after partial digestion of the $Tc^r$ plasmid pKHl with HindIII and sequence determination of that fragment were carried out. Analysis of the sequences revealed that the 4570-bp HindIII fragment contained a 4011-bp fragment of the small $Tc^r$ plasmid pKH6 flanked by the partial sequences of IS431mec. It was concluded from the above result that the pKHl was produced by integration of the partial sequence of the pKH6 into another plasmid via IS431mec.