Authors analyzed the findings of chest radiographs and high-resolution CT (HRCT) of chronic mercury vapor poisoning in 12 patients who were diagnosed by previous working history for mercury- thermometer and high level of merucry in blood and urine. The purpose of this paper is to introduce the HRCT findings of chronic mercury vapor poisoning. Duration of mercury exposure was ranged from 10 to 41 months(mean, 21.8 months). Estimated value of serum mercury was ranged from 3.6 to 8.7$mu extrm{g}$/dI(mean, 5.3$mu extrm{g}$/dI : normal value is less than 0.5$mu extrm{g}$/dI). Estimated value of mercury in urine was ranged from 104 to 482$mu extrm{g}$1(mean, 291.4$mu extrm{g}$/1:normal value is less than 20$mu extrm{g}$ /1). Chest radiographs showed positive findings such as ground-glass opacities and peribronchial cuffings in only 2 out of 12 patients, but HRCT showed positive findings such as ground-glass opacities in 8 patients. peribronchial cuffings in 7 patients, centrilobular abnormalities in 5 patients, interface sign in 4 patients, interlobular septal thickening with intralobular lines in 2 patients and lobular consolidation in one partient. In conclusion, chest HRCT is superior to chest radiograph to show the pulmonary manifestation of chronic mercury vapor poisoning. In patients with chronic mercury vapor poisoning. HRCT findings of centrilobular distributed ground-glass opacities and peribronchial cuffinges are characteristic.