Objectives: To ascertain whether some result of hematological examination could be as reference data for health management of welders. Method: The authors conducted the hematological examination of 1,018 welders and 531 control workers of a shipbuilding industry in Ulsan using automatic blood analyzer. Results: The WBC count of welders was lower than that of control on controlling the age and the duration of employment, but changes of other blood cells were not observed. Conclusion: We could use the results of hematological examination such as WBC counts as an indicator for subtle changes of health status of welders.