Background: Staphylococcus aureus is one of the main agents of nosocomial infections. Identifying coagulase enzyme in staphylococcal infections is of great importance as it is one of the main virulence agents. The present study aims to accurately detect the presence of coagulase gene and its relationship with antibiotic resistance patterns in clinical isolates. Methods: In this experimental study, a total of 20 clinical samples of S. aureus and 10 clinical samples of coagulase-negative staphylococci were collected and identified from hospitals and laboratories in Nowshahr and Chalous. Antibiotic resistance patterns of isolates were examined based on CLSI and finally polymerase chain reaction was used in order to detect the presence of coagulase gene with specific primers. Treatments were examined in three intervals and the results were analyzed using one-way analysis of variance (ANOVA), univariate ANOVA, and t-test at the probability level of P < 0.05. Moreover, the comparison of means was presented using Duncan's multiple range tests (P < 0.05). All the statistical analyses were carried out using SPSS (V. 16). Results: Suggested that isolates showed phenotypic presence of coagulase enzyme and had this gene genotypically as well. Coagulase-positive samples demonstrated higher resistance to tetracycline 20%, oxacillin 55%, gentamicin 20%, and kanamycin 25%. Statistically, there was no significant difference among inhibition zone diameters of oxacillin, nalidixic acid, gentamicin, kanamycin, and penicillin. Conclusions: Coagulase gene causes antibiotic resistance and coagulase-negative staphylococci are spreading rapidly and their resistance is increasing.