This study was conducted to evaluate the relationships between the environmental exposure and biological monitoring among workers exposed to metallic mercury We interviewed each workers to get the medical history including previous hazardous occupational history. We measured the respiration rate and tidal volume of each worker in order to calculate the 8-hour inhaled mercury of workers. And we wafted to evaluate the effect of exposure duration to mercury concentrations in blood and urine as biologic exposure indices of metallic mercury. The regression and correlation analysis were done to the relationships of 8-hour inhaled mercury and mercury in blood and urine. The results were as follows; 1. The subjects were 35 fluorescent lamp manufacturing workers. The mean age of subjects was .24.8 years old, and the mean work careers of workers was 1.19 years. 89% of the total was consisted man. 2. The correlation coefficients between 8-hour inhaled mercury and mercury in blood and urine were higher than that of only considered air mercury concentration. 3. The correlation coefficients of 8-hour inhaled mercury and mercury in blood and urine were above 0.9 in workers who had exposed to mercury more than 1 year 4. The R-square value and -value of regression analysis between the 8-hour inhaled mercury and mercury in blood and urine was also higher in workers who had exposed to mercury over 1 year than in workers who had less than 1 year working experience. The important results of this study were that relationships between the 8hr-inhaled mercury and mercury in blood and urine was very high than that with air mercury concentration only. And the results were very apparent when considering workers 1 year or more. Therefore we concluded that the work career and respiratory volume of each individuals should be considered in evaluation the, results of biological monitoring of workers exposed to metallic mercury.