A survey of 145 Japanese hospitals revealed the use of 4 inappropriate aldehyde disinfection methods in 5.5% to 16.8%. Following education, there was discontinuation of 3 of these practices in 26 of 28 affected centers, but only 4 of 18 affected centers stopped the use of formaldehyde vapor cabinets. There is a need to inform hospitals about inappropriate disinfection methods that pose chemical risks to patients and staff.