A fire at the Cleveland Clinic in Cleveland, Ohio kills 123.

A major structure fire occurred at the Cleveland Clinic in Cleveland, Ohio, United States, on May 15, 1929. Flammable nitrocellulose X-ray film ignited in a basement storage room, emitting a poisonous yellowish-brown gas which spread throughout much of the Clinic and subsequently exploded several times. The fire claimed 123 lives including that of one of the Clinic's founders, Dr. John Phillips. Most of the deaths from the fire were due to toxic inhalation. Many were immediate; some were delayed by hours or even days. A policeman, Ernest Staab, rescued 21 victims from the fire, and left the scene, seemingly in good health. He later collapsed while working on his lawn, was hospitalized, but contrary to many contemporaneous newspaper articles survived and worked for the police department for another 25 years.

Cleveland Clinic is an American nonprofit academic medical center based in Cleveland, Ohio. Owned and operated by the Cleveland Clinic Foundation, an Ohio nonprofit corporation, Cleveland Clinic was founded in 1921 by a group of faculty and alumni from the Case Western Reserve University School of Medicine.

Cleveland is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located along the southern shore of Lake Erie, it is situated across the Canada–U.S. maritime border and approximately 60 mi (97 km) west of the Ohio–Pennsylvania state border. Cleveland is the most populous city on Lake Erie and second-most populous city in Ohio with a population of 372,624 at the 2020 census, while the Cleveland metropolitan area with an estimated 2.17 million residents is the 34th-largest metropolitan area in the United States.