Squamous cell carcinoma of the head and neck is a devastating illness with a severe impact on affected individuals. Several mechanisms may lead to oxidative stress in tumor-bearing patients, among others chronic inflammation. Inflammatory cells, especially macrophages and neutrophil leukocytes, may produce reactive oxygen species (ROS) which participate in carcinogenesis and tumor-associated immunosuppression. The aim of the study presented in this paper was to compare the production of reactive oxygen species (ROS)--superoxide anion (O2-) and hydrogen peroxide (H2O2)--by neutrophils isolated from the blood of 16 patients with larynx carcinoma and 15 healthy controls. The serum activity of superoxide dismutase and catalase as well as the total peroxidase activity in serum have also been estimated. The production of ROS, especially spontaneous and phorbol 12-myristate 13-acetate (PMA)-induced O2-, was relatively higher in the patients with larynx carcinoma than in the healthy controls and increased parallel with the tumor stage (tumor, node, metastasis-TNM staging). The serum activity of catalase and peroxidase was also highest in the patients with stage T3 and T4 larynx carcinoma. After partial or total laryngectomy, a significant decrease in ROS production and the serum activity of catalase and peroxidase was observed. In contrast, the serum level of superoxide dismutase, which had been low prior to surgery, especially in the patients with advanced tumor stages (T3-T4), increased significantly afterwards. The results indicate the existence of oxidative stress in the blood of patients with larynx carcinoma and its significant decrease after partial or total laryngectomy.