Normal 0 false false false EN-US X-NONE AR-SA In current study, we reported a research on contamination of instruments and frames of removable partial dentures transmitted from laboratory to the clinic. The instruments and frames were sampled three times and the obtained samples were cultivated in special mediums. Then, the resulted colonies were again sampled to achieve unified bacterial strains and finally the bacteria strains were analyzed in biologic, biochemistry and serological characteristics. The obtained results are presented in this article.