Oxidative stress plays an important role in the pathogenesis of some diseases. Smoking may enhance oxidative stress not only through the production of reactive oxygen radicals in smoke but also through weakening of the antioxidant defense systems. Study done To assess the erythrocyte superoxide dismutase activity in cigarette smokers. This is case control study. The study was conducted from February to May 2015, sixty samples from non smokers chosen randomly as control and sixty sample from smoker as test group. All samples were tested for superoxide dismutase activity using fortress diagnostic reagent by spectrophotometer analyzer, and results were analyzed using statistical of package social science. The study result showed that the level of superoxide dismutase activity was significantly decrease (P = 0.00) in smokers. Mean ± SD cases versus controls (907±134.47 versus 1159±93.44). There are a significant moderate negative correlation with the number of cigarettes per day (P = 0.00) also weak negative correlation with duration of smoking (P = 0.048).From this study, concluded that superoxide dismutase level was significantly decreased in smokers and correlated negatively with number of cigarettes and duration.