Oral squamous cell carcinoma (OSCCs) is one of the most prevalent types of all oral neoplasms that highly require early diagnosis. Salivary evaluation is non-invasive, simple, and rapid.The aim of the current study was to investigate the relationship between salivary MMP-9 concentration and its tissue expression in patients with OSCC.Materials and Methods: Saliva samples were collected from 24 patients with primary diagnosis of OSCC and 24 healthy age-and-gender- matched. The unstipulated saliva was collected with spitting method. After saliva collection, the tissue samples were obtained by biopsy. Salivary concentration and tissue expression of MMP-9 were evaluated using ELISA and immune histochemistry assays, respectively. Data were analyzed using t-test, chi-square, and ANOVA tests with the confidence interval of 95%. Results: A significant increase in salivary concentration of MMP-9 was evident in OSCC patients in comparison to healthy individuals (P-value < 0.05).In addition, the MMP-9 salivary concentration was significantly higher in males in comparison with females (P-value < 0.05). There was a positive and significant correlation between salivary concentration of MMP-9 and its tissue expression (Pearson Correlation = 0.669, P-value< 0.05). Conclusion: Salivary evaluation of MMP-9 concentration could be a valuable tool to detect OSCC.