During the periodic physical checkups in 1997-2000, the authors have found eleven cases of nasal septum perforation among 2, 869 welders in Ulsan, Korea. They have not suffered from diseases and conditions that could cause septum perforation such as tuberculosis, syphilis, and longterm use of topical corticosteroids. And also they did not have trauma history and surgical experiences on their nasal septum. To investigate the cause of septum perforation we reviewed the past history of pre-employment, the results of annual working environment survey and the material safety data sheets of welding rods and steels with which they have dealt. We also analyzed the concentration of several metals of welding fume and the concentration of blood and urinary chromium. In the result, we assumed that the nasal septum perforation of welders was due to chronic exposure to low-level hexavalent chromium.