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Pulmonary injury after acute H

2

S inhalation was studied with bronchoalveolar lavage（BAL）

ultracentrifuge

and optical and electron microscopy.The changes of the activities oflactate dehydrogenase

alkaline and acid phosphatase

and angiotension converting enzymes inBAL fluid were used as the indicator of cellular damages

those of leucocytic count and the indi-cator of inflammatory response

and those of the concentration of protein and Evans blue as theindicator of vascular permeability.In addition the effects of H

2

S on lipid peroxidation

naturalantioxidative system and energy substances and the changes of phospholipid concentration inBAL fluid were also observed.The results were as follows:1.Inhalation of H

2

S exerted a severe cytotoxic effect on the lung tissues resulting in dam-ages on various types of cells and a severe edematogenic effect on lung parenchyma.2.The development of pulmonary edema in H

2

S intoxication resulted from a combination ofdifferent pathogenic factors.3.The biochemical changes and their recovery occurred earlier than the pathologicalchanges and their recovery.The efficacy of 6 categories of drugs including 25 medicaments against H

2

S intoxication wasevaluated in mice

and 10 drugs were found to be prophylactically effective.The effects of vari-ous methemoglobin-forming agents and some other drugs were also studied in their treatment ofH

2

S intoxication in rabbits and dogs.It was concluded that methemoglobin-forming agentscould be used as specific antidotes but could not provent or alleviate the lung damages due toH

2

S inhalation unless they were administered in association with dexamethasone

vitamin E oranisodamine.A scheme of the medical treatment for H

2

S intoxication was presented.