To The Editor:— Isoproterenol hydrochloride has been in use for approximately eight years as a bronchodilator. It is most commonly administered as an aerosol spray from hand nebulizers. While paradoxical reactions have been noted with isoproterenol hydrochloride, 1 to the best of our knowledge no cases of allergy to this drug have been reported. Recently, we had the opportunity to study a case which may represent such allergy. This was the tenth Albany (NY) Veterans Administration Hospital admission for a 48-year-old white man known to have severe emphysema and chronic bronchitis. The patient was told he had "asthma" as a child. Eight years prior to the present admission, he was said to have emphysema. Positive skin reactions to dust and wool had been noted. The present admission was precipitated by a bout of shortness of breath and increased cough of three days' duration. A therapeutic regimen was instituted including intravenously