Purpose This study aimed to investigate the relationship between oxidative stress levels in the tumor center, tumor edge, and healthy tissue. Methods This study included a total of 53 patients with head and neck cancer. Samples of 5 x 5 x 5 mm were collected from the tumor center, tumor edge, and the healthy tissue. Total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) values were evaluated. (1) Oxidative stress values in the center and edge of all tumors and in healthy tissues were compared according to localization. (2) Tumors were divided into two groups as malignant (Group 1 [n = 28]: Laryngeal and tongue squamous cell cancers) and benign (Group 2 [n = 25]: Pleomorphic adenoma and Warthin tumors). The groups were compared according to the localization of the tissues. Results The TOS value in the tumor edge was significantly higher than those in the tumor center and the healthy tissue. The TAS value in tissue located in the tumor edge was significantly higher than in the healthy tissue. The OSI value in the tumor edge was significantly higher than those in the tumor center and the healthy tissue. In all three localizations (tumor center, tumor edge, and healthy tissue), TOS and OSI values in Group 1 were significantly higher than Group 2. Conclusion Oxidative stress values in the tumor edge are significantly higher than the center of the tumor and healthy tissue. In malignant tumors, oxidative stress values are significantly higher in all localizations compared to benign tumors.