--Introduction: Oral Squamous cell carcinoma is a common malignancy worldwide. MicroRNAs (miRNAs) are short, non-codi ng RNAs that are f ound t o be up or down-regulated in Oral cancer patients and play a role in all levels of carcinogenesis. It regulates the post-transcriptional levels of t arget ed mRNAs. The miRNA-21 (miR-21) i s upregulated in oral carcinoma status. We studied the expression of miRNA 21 in plasma of Oral squamous cell carcinoma patients. Materi als and methods: We observed the levels of miR-21 in plasma of patients with OSCC (n 30) and healthy controls (n 30) by miRNA easy kit quagen. The fold change was observed and compared with OSCC and controls. Results: Plasma miR-21 levels were increased markedly in the patients with OSCC compared to controls. The patients with moderately differentiated, Stage-IV OSCC patients s howed i ncreased f old change compared t o well-differentiated and Stage-III OSCC patients. Conclusion: Our results indicate that plasma miR-21 may be used as an adjuvant biomarker the detection of OSCC patient. © 2023 Elsevier B.V., All rights reserved.