Welding is a process during which fumes, gases, electromagnetic radiation and noise are emitted as by-products. Metal oxide particles are particularly hazardous components of welding fumes. Welding has been found to be associated with respiratory symptoms and our objective in the present study was to study the effects of welding on pulmonary function and serum oxidant-antioxidant status. Fifty-one welding workers and 31 control subjects were recruited. Face to face interviews were conducted using the respiratory illness questionnaire adapted from the American Thoracic Society with the addition of demographic characteristics, work history and working conditions. Additionally physical examinations and spirometric measurements were performed at workplaces. Thiobarbituric acid reactive substances (TBARS), protein carbonyls, protein sulfhydryls (SH) and erythrocyte reduced glutathione (GSH) levels were measured to evaluate oxidant-antioxidant status in 34 welding workers and in 20 control subjects. No statistically significant differences were observed in age, height, weight, body mass index (BMI), smoking status and annual working durations between welding workers and controls. Coughing, sputting and wheezing were significantly higher in welding workers (p<0.05). When adjusted for age, BMI and smoking status in logistic regression, welding work showed a significant risk for chronic bronchitis (OR: 4.78, 95%CI: 1.30-17.54). Forced expiratory volume in one second (FEV(1))/forced vital capacity (FVC) and four parameters of forced expiratory flow (FEF: FEF(25), FEF(50), FEF(75), FEF(25-75)) levels measured in the welding workers were significantly lower than those in the control group (p<0.05). Serum TBARS and protein carbonyl levels were higher in welding workers than those in controls (p<0.001, p<0.05, respectively). On the other hand, total protein SH groups and GSH levels were significantly lower in welders than those in controls (p<0.05, p<0.001, respectively). Pulmonary function tests and oxidant-antioxidant status were found to be negatively affected in welding workers chronically exposed to welding fumes and gases. Preventive measures should be taken to improve the health status of these workers.