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Introduction: Given the importance of zinc metal (zn+2) as an essential element in boil-ogical systems and the toxic effects of metals, on the other hand, and the emerg-ence of strains of Staphylococcus aureus (S. aureus) smr+ resistant to tetravalent amm-onium compounds (QACs) due to widesp-read use of materials containing Biocide QACs led to compare the sensitivity of S. aureus strains resistant to zinc and those strains having the biocide benzalkonium chloride and smr genes. Materials & Methods: S. aureus strains isolation from dairy and clinical samples was performed by using of mannitol-salt-agar medium at 37 ° C for 48 hours and the strains was identified with morphological and biochemical methods. The Smr gene was investigated by PCR and the minimum inhibitory concentration (MIC) of zinc for the bacterial strains was determined using broth microdilution. Findings: 20 strains of S. aureus were sele-ctively isolated from 40 samples of dairy and clinical. Smr genes were observed in all S. aureus strains resistant to the biocide benzalkonium chloride. The MIC concentr-ation was reported to be ppm 20. Discussion & Conclusion: The results showed that the growth of all strains of S. aureus, that is, the susceptible and the resis-tant to benzalkonium biocide zinc chloride substance is inhibited in 20 ppm concentr-ation of zinc and the presence of smr gene has no effect on resistance to zinc.