Welders are exposed to fumes containing different gases, fumes and particles, depending on the composition of the welding electrodes, welded material and the welding method used. Welders are workers at risk of developing various respiratory signs and symptoms. Health effects associated with welding include different lung function abnormalities, including metal fume fever, bronchial asthma, chronic obstructive pulmonary disease, pneumoconiosis and other pulmonary fibrosis (chronic beryllium disease, cobalt lung), and lung cancer. The authors describe some aspects of etiology, pathogenesis, diagnostics, prophylaxis, and medical certification of welding-related respiratory diseases. Med Pr 2009;60(3):201-208