Inhalation of vaporized 1 per cent solution of epinephrine is extensively used in the relief of bronchial asthma.1This is a convenient way of obtaining directly the well known bronchodilator action of epinephrine without the necessity of hypodermic injection. The clinical results have been generally good as to relief of asthmatic attacks. At least ten atomizers are advertized as specially designed for this purpose, and, in addition, 1 per cent solution of epinephrine is the active ingredient of a large number of trade-marked anti-asthma products offered to the public. In spite of the widespread use of this strong concentration of epinephrine, no reports have been made as to possible local irritative effects on the respiratory tract. When it is remembered that deep inhalations of this potent drug are practiced almost indefinitely in a chronic disease state, it would appear desirable to understand more fully and definitely, if possible, the