Objectives: The aim of the study was to evaluate the effects of repeated Finnish sauna baths on the concentrations of nitric oxide metabolites (NO_x) and 3-nitrotyrosine in relation to pro-oxidative and antioxidative status in young males with different physical activity levels. Material and Methods: The study was performed on healthy males (aged 20–25 years), representing the training (T, N = 10) and non-training groups (NT, N = 10). The protocol included a series of 10 sauna baths during 3 weeks. One bath consisted of three 15-min sessions, with 2 min recovery. Before the first and the 10th treatment, measurements of body composition, blood pressure, rectal temperature, and plasma concentrations of the total pro-oxidative and antioxidative status, 3-nitrotyrosine and NO_x were performed. Results: A significant increase in physiological parameters during sauna treatments, as well as a significant decrease in the total antioxidative status before the 10th bath, were observed in both groups. The series of sauna baths caused a significant increase in the total antioxidative status in the T group, and a decrease in the total oxidative status in the NT group. A significant decrease in 3-nitrotyrosine in both groups before the last treatment, and also in the T group after the last treatment, was noted. In both groups, a significant increase in NO_x concentrations was observed after the first bath. Conclusions: A series of sauna baths contributes to the improvement in the prooxidative/ antioxidative balance. The increased production of nitric oxide may lead to a better vascular relaxation and blood flow. Int J Occup Med Environ Health. 2020;33(2):173–85