en Epidemiologic studies including microbial genotyping, phenotyping and serotyping Epidemiologic studies including microbial genotyping, phenotyping and serotyping Original article Original article <strong>Introduction: </strong><em>Staphylococcus aureus </em>is among the primary cause of hospitals and community-acquired infections. The emergence of methicillin-resistant <em>S. aureus </em>(MRSA) strains has resulted in the treatment failure of the infections caused by these bacteria. Hence, regional data on antibiotic resistance of <em>S. aureus</em> strains is necessary to adopt appropriate treatment regimens. This study aims to identify the diversities and their frequencies among MRSA isolates by molecular analysis of four genes. <strong>Methods:</strong> In a cross-sectional study, 100 <em>S. aureus</em> isolates from patients hospitalized in two hospitals of Ahvaz, Iran were collected and identified. The MRSA isolates were identified by phenotypic method and amplification of the <em>mec</em>A gene. The diversity of MRSA isolates was investigated by amplification of the <em>coa</em>, <em>spa</em>, <em>aro</em>A, and <em>gap </em>genes followed by RFLP analysis using the <em>Alu</em>I, <em>Hind</em>III, <em>Taq</em>I and <em>Rsa</em>I restriction enzymes. <strong>Results:</strong> In this study, we identified 50 MRSA isolates. Based on the analysis of <em>coa</em> gene, 8 types, <em>spa</em> gene 5 types and 17 subtypes, <em>coa </em>gene with <em>Alu</em>I 13 types, and <em>spa</em> with <em>Hind</em>III 13 types were identified. Also, the RFLP analysis of <em>gap </em>gene with <em>Alu</em>I revealed 3 types, and of <em>aro</em>A gene with <em>Taq</em>I and <em>Rsa</em>I, 3 types and 2 subtypes, respectively.&nbsp; <strong>Conclusion:</strong> Our PCR-RFLP analysis revealed that diversities are present among MRSA isolates originated from clinical samples and showed that this method is simple, reproducible, and cost-effective.&nbsp; Methicillin-resistant, Staphylococcus aureus, genetic diversity, Iran 19 28 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-181-1&slc_lang=en&sid=1 Elahe Soltani Fard es.unichamran@gmail.com 0000-0001-9625-2154 No Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran Mohammad Roayaei Ardakani roayaei_m@yahoo.com 0000-0003-4140-4303 No Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran Hossein Motamedi hhmotamedi@yahoo.com 0000-0003-0310-7017 Yes Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran