Objectives: To compare the preoperative Red Cell Distribution Width (RDW) value in curatively-operated gastric cancer (GC) patients without receiving neoadjuvant chemotherapy (NACT) vs. control group, with the aim of investigating its preoperative prognostic effect. Methods: Receiver Operator Characteristics (ROC) curve of RDW value was plotted for DFS. The area under curve (AUC) of the RDW was 0.714 with 73.5% sensitivity and >5.5 with 71.1% specificity. Patients were divided into 2 groups as RDW ?15.5 and RDW >15.5. Results: The study included 330 GC patients (37.7% female and 62.3% male) and 330 healthy controls (63.9% male and 36.1% female). ROC curves were used to confirm the predictive role of preoperative RDW value in predicting the presence of GC. For GC, the AUC of RDW was 0.665 with 61.3% sensitivity and 14.1 with 64% specificity. There was a positive correlation between disease stage and RDW in GC patients (Rho=0.338, p<0.001). Five-year DFS was 81.1% in the low-RDW group and 61.9% in the high-RDW group (p=0.001). Similarly, Corresponding 5-year overall survival (OS) rates were 74.4% and 57.7 (p=0.001). In multivariate analysis, male gender, stage III disease, high CEA, and RDW ?15.5 were the factors associated with worse DFS, whereas adjuvant therapy (p=0.036) prolonged DFS significantly. Conclusion: In our study, preoperative RDW was found to be both predictive and prognostic for GC.