The aim of this study was to determine levels of serum 8-hydroxy-2'-deoxyguanosine (8-OHdG) as an indicator of oxidant-induced DNA damage and oxidant status in patients with papillary thyroid carcinoma before and after surgery. This study included 25 patients with papillary thyroid carcinoma and age-matched 27 healthy controls. Total antioxidant status (TAS), total oxidant status (TOS), lipid hydroperoxide (LOOH), and 8-OHdG levels were measured. 8-OHdG levels were significantly higher in the preoperative papillary thyroid carcinoma (PTC) group compared with the healthy control group (p < 0.001) and were significantly lower after operation in patients with papillary thyroid carcinoma (p = 0.004). Oxidative stress index (OSI) levels were significantly higher in both preoperative and postoperative PTC patients compared with the healthy control group (p < 0.001 and p < 0.001, respectively). TOS levels were higher in the preoperative and postoperative PTC groups compared to the healthy control group (p < 0.001 and p < 0.001, respectively). TAS levels was lower in the preoperative PTC groups compared to the healthy control group (p = 0.011). Serum LOOH levels were higher in both preoperative and postoperative PTC groups compared to the healthy control group (p < 0.001 and p < 0.001, respectively). Correlation analysis yielded that serum 8-OHdG levels were positively correlated with OSİ and LOOH levels in patients with PTC before surgery (r = 0.668, p < 0.001; r = 0.446, p = 0.025, respectively) and had a negative correlation with TAS levels (r = -0.616, p = 0.001). We have shown severe oxidative DNA damage and impaired antioxidant status in papillary thyroid carcinoma.