Epidemiologic studies have identified cleaners as an occupational group at increased risk of asthma and asthma-type respiratory symptoms. The level of increased risk in cleaners for these respiratory problems has ranged from around 1.5 to 2.5 times the background risk. Specific chemicals in cleaning products identified to cause sensitization include disinfectants (chloramine, chlorhexidine, formaldehyde, glutaraldehyde, and hexachlorophene); amine compounds (amino alcohols, aliphatic polyamines, and the quaternary amine, benzalkonium chloride); tall oil; the fungicide tributyltin oxide; and enzymes produced by Bacillus subtilis and other additives used in detergents. The mixing of cleaning products containing bleach and acid or bleach and ammonia, which causes the production of chlorine or chloramines, as well as the use of strong irritants to clean such as hydrofluoric acid have caused reactive airways dysfunction syndrome. Further research is needed to better elucidate the respiratory disease among cleaners. Questions that need to be resolved include: How much of the respiratory symptoms in cleaners are secondary to sensitization to ingredients of certain cleaning products, how much to their irritative properties, and how much to exposure to environmental allergens such as dust mites whose immunologic effect may be heightened by certain cleaning products? In the meantime, clinicians need to be aware when evaluating patients with asthma or asthma-like symptoms that cleaning agents at work or at home may be important triggers that are either initiating or aggravating the patient's disease.