The lung is the route of entrance and exit of the commonly employed halogenated inhalation anesthetics. Biotransformation of anesthetics can under certain circumstances produce harmful products and/or reactive intermediates. It is the intent of our proposed study to ascertain the qualitative and quantitative aspects of halogenated anesthetic biotransformation under a variety of environmental influences using the rabbit lung as a model. Our investigations may cast light on a heretofore unrecognized area of anesthetic activity and may give insight into the problem of post-anesthetic pulmonary dysfunction.