Background: Inhalation of mercury vapor is very rare, but if it occurs, fatal damage, such as acute lung injury or death, may ensure. In addition, acute generalized exanthematous pustulosis due to mercury hypersensitivity has rarely been reported in the literature. We experienced a 49-year-old male patient who had been exposed to mercury vapor following burning of mercury-containing materials. Case History: The patient complained of dyspnea, fever, and systemic erythema. Physical examination revealed that he had macular erythema with tiny pustules. His body temperature was 38.3oC and a complete blood count revealed elevated leucocytes. Chest radiographs revealed diffuse airspace opacification in both lungs. Results: He was admitted to the intensive care unit and treated with oxygen, intravenous methylprednisolone 125 mg per day, and oral antihistamines. His symptoms improved and his skin lesions resolved completely with desquamation 5 days. On the eighth hospital day, intravenous methylprednisolve was tapered to 62.5 mg methyprednisolone, followed by oral methyprednisolone. He was discharged from the hospital on the 20th hospital day and is currently being followed-up with no aggravation of symptoms or relapse. Conclusion: We report a case of acute lung injury and acute generalized exanthematous pustulosis induced by inhalation of mercury vapor that was successfully treated with early avoidance and steroid therapy.