The light-dark cycle represents a significant component of the circadian system in most mammals. Any disturbance of this cycle is reflected in a large number of changes in the physiological and also behavioral status of the organism, together with considerable alterations of the redox balance. Increasing evidence suggests that reactive oxygen species (ROS) have their own function in the circadian system. Superoxide dismutases (SOD) family represents the first prompt antioxidant enzymatic system, identified in all aerobic organisms and able to counteract ROS toxicity; there are three distinct isoenzymes: CuZn-SOD (SOD1), Mn-SOD (SOD2), and extracellular EC-SOD (SOD3). In the case of circadian disruption, when ROS production is enhanced, the impact of the oxidative aggression on superoxide dismutases (SOD) rhythmicity and distribution is still unclear. To estimate the influence of circadian rhythms disruption on pulmonary SOD, we exposed male Wistar rats to continuous light stimuli for four weeks and then investigated the SOD immunohistochemical expression in lungs, which are among the most sensitive organs to oxygen. CuZn-SOD, Mn-SOD and EC-SOD presented a particular immunoreactivity in the investigated pulmonary tissues. These findings support our viewpoint that there is a direct correlation between the rhythmicity of circadian cycles and pulmonary SOD expression.