Lead in various forms has been recognized for a long time as one of the important occupational poisons. The zealous study and the insistent presentation of the characteristics of the condition have outlined a clinical picture which is a matter of general medical instruction and knowledge, in spite of the controversial nature of certain diagnostic details. The manufacture and handling of tetra-ethyl lead, resultant on its recent development for important industrial purposes, has brought about the appearance of a type of lead poisoning which, because of its unique character, is made the subject of this paper. Tetra-ethyl lead is a clear, heavy (specific gravity about 1.62), oily liquid with a peculiar sweetish odor, which is somewhat volatile at ordinary temperatures. It is insoluble in either hot or cold water, but soluble in alcohol and acetone, and miscible in all proportions with fats and oils. It decomposes in the presence of