Abstract: Objective To investigate adverse effects of occupational exposure to mercury on workers. Methods Totally 1 002 workers occupationally exposed to mercury were studied and their health examination data were compared with 805 workers without any records of exposure to known occupational hazards. they were received examination of blood pressure, electrocardiogram,alanine aminotransferase (ALT),routine blood test, routine urine test, kidney functions(BUN and B-Cr),urine mercury and urine β₂-MG. Results The mercury concentrations at 60 measured workplaces were lower than 0.02 mg/m³. The blood pressure, electrocardiogram, urine routine tests, blood routine test, kidney functions, and urinary mercury showed no significant changes compared with those in the non-exposed workers(P>0.05). However, urine β₂-MG of exposed workers was higher (P<0.05). urine β₂-MG and urinary mercury concentrations of exposed workers were both related to employment time (r=0.995 8,0.952 2, respectively, P<0.05). Conclusion Urine β₂-MG is an earlier indicator for change of kidney functions caused by mercury. It is necessary to examine urine β₂-MG when we do occupational health examination for mercury exposed workers.