Born in St. Lawrence County, New York, Keeley graduated at the Rush Medical College, Chicago, in 1863, and later entered the Union Army as a surgeon. At the end of the war he moved to Dwight, Ill., where he began his private medical practice. There, in 1880, he opened a sanatorium for persons addicted to the immoderate use of alcohol and opium. He asserted that "Alcoholism is a disease and I can cure it." His treatment centered on a secret preparation that he said contained bichloride of gold. However, chemical analysis revealed that the proprietary tonic contained 27.55% alcohol plus ammonium chloride, aloin and tincture of cinchonaa but no gold. His hypodermic injections contained sulfate of strychnine, atropine and boracic acid.
In 1939, Time magazine reported that "Unvarying is the traditional Keeley routine. An incoming inebriate pays $160, plus room and board, must stay for 31 days. His weekly whiskey ration is gradually tapered off: eight ounces the first day, six ounces the second, four ounces the third, none from there on. Four times a day he gets gold chloride injections; every two hours he takes a tonic."  At its height, the clinic in Dwight treated 700 patients per day.
Keeley claimed that when his medicine was administered according to his directions, it had no injurious effects and that 95 per cent of the patients were permanently cured. If they did return to drinking, he insisted that they were cured but that they drank because they choose to do so, not because they were still addicted.
Keeley published numerous articles in the popular press in addition to pamphlets promoting his therapy, and wrote The Morphine Eater, or From Bondage to Freedom (1881) and the Non-Heredity of Inebriety (1896).
The Keeley Institute in Dwight was the last to close, doing so in 1966.Jared Lobdell (1 June 2004). This Strange Illness: Alcoholism and Bill W.. Aldine. p. 51. ISBN 978-0-202-30739-8. Retrieved 21 April 2012.</ref> Despite the modern assumption that Keeley's therapy was merely a successful example of quackery, Keeley is remembered as one of the first to treat alcoholism as a medical problem.
- Keeley cure – a proprietary method of treatment for the alcohol and opium habits by means of gold chloride. (The American Illustrated Medical Dictionary, 1938 edition.)
- This article incorporates text from a publication now in the public domain: Gilman, D. C.; Thurston, H. T.; Moore, F., eds. (1905). "article name needed". New International Encyclopedia (1st ed.). New York: Dodd, Mead.
- AUTHOR OF KEELEY CURE DEAD; Dr. Leslie E. Keeley Succumbs to Heart Disease at Los Angeles – Leaves Estate of $1,000,000. New York Times, February 21, 1900
- Some sources claim he was born in Ireland; the birth year also varies from 1832 to 1836
- "The Keeley 'gold cure' for inebriety". British Medical Journal 2: 85. 1892. doi:10.1136/bmj.2.1645.85.
- James Roosevelt, In Sickness and Health. Appleton, 1896, p. 79
- University of New Brunswick Archives & Special Collections-The Leslie E. Keeley Institutes of the Maritime Provinces Company (Fredericton, N.B.) fonds. Lib.unb.ca. Retrieved on 2012-04-21.
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- Keeley cure, Time, September 25, 1939
- If Dr. Keeley Could See You Now, Wall Street Journal, December 31, 2007, p. B1
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