Abstract: Objective:To explore the changes of salivary thioredoxin(Trx)levels and its diagnostic and prognostic value in patients with oral squamous cell carcinoma (OSCC).Methods:A total of 106 patients with OSCC(OSCC group)and 212 healthy volunteers(control group)were selected from Puren Hospital affiliated to Wuhan University of Science and Technology from January 2016 to December 2019.Sociodemographic information such as age, gender, health-related behavioral variables such as smoking and drinking, and potential influencing factors such as periodontitis and hypertension were collected from the two groups.Saliva Trx levels were detected by enzyme-linked immunosorbent assay.Overall survival (OS) was recorded during follow-up.Results:The salivary Trx levels of OSCC patients were significantly higher than those of the control group (P< 0.001).After controlling for various confounding factors, increased salivary Trx levels were associated with the risk of OSCC(OR=1.042, P< 0.001).The receiver operating characteristic curve analysis showed that the area under the curve of baseline salivary Trx for OSCC diagnosis was 0.958(95%CI:0.928-0.988, P< 0.001).The salivary Trx levels in OSCC patients continued to decrease during follow-up, and decreased by 74.8%at 9 months after surgery compared with baseline, but they were still higher than those of the control group (P< 0.05).Kaplan-Meier survival curves were drawn, the overall survival rates of high Trx subgroup and low Trx subgroup were 37.25%(19/51) and 70.00% (35/50), respectively (Log Rank χ²=13.636, P< 0.001), and the relapse-free survival rates were 43.14% (22/51) and 70.00% (35/50), respectively (χ²=11.184, P=0.001).Univariate and multivariate Cox regression analysis showed that baseline salivary Trx le-vel≥1, 628.68 U/L was a risk factor for adverse OS in OSCC patients (P< 0.05).Conclusion:Salivary Trx can be used as a candidate biomarker for diagnosis and prognosis of OSCC.