BACKGROUND Data describing how laryngeal cancer affects oxidative stress markers and antioxidants are limited. This study investigated serum antioxidant enzyme activities and oxidative stress markers before and after laryngectomies in patients with laryngeal cancer. METHODS A total of 29 patients with laryngeal cancer and 25 healthy control subjects were enrolled. Serum malondialdehyde (MDA) levels and superoxide dismutase (SOD), glutathione peroxidase (GSHPx), catalase (CAT), paraoxonase (PON), and arylesterase activities were measured spectrophotometrically. Blood samples were obtained from each patient just before surgery and 1 month after a laryngectomy. RESULTS The serum PON, arylesterase, CAT, SOD, and GSHPx activities were significantly decreased (all p < 0.001) and serum MDA levels were significantly increased (p < 0.001) in patients with laryngeal cancer, compared with control subjects. In laryngeal cancer patients, the serum GSHPx and arylesterase activity levels increased significantly following laryngectomies (both p < 0.001), whereas the MDA levels decreased significantly (p = 0.007). CONCLUSIONS In patients with laryngeal cancer, the oxidant/antioxidant balance shifted toward oxidative stress. In addition, following laryngectomies, laryngeal cancer patients had increases in serum antioxidant enzyme activities and decreases in oxidative stress markers.