Healthcare workers are exposed to a variety of chemical agents used in many different areas and purposes. The chemicals could cause health problems to healthcare workers using them. Glutaraldehyde is a kind of disinfectant and used for endoscopes, catheters, and many kinds of operating apparatus. It may cause allergic contact dermatitis. Formaldehyde is another disinfectant and can be used for fixing tissues. Formaldehyde was classified to a Group 1 carcinogen by IARC and it may cause lung or nasal cancer. Ethylene Oxide gas is the most popular disinfectant these days and may be applied to many health care sets or linens. EO gas may cause allergic contact dermatitis and breast cancer or leukemia. It is also classified as Group 1 carcinogen despite limited evidence for human cancers. Anesthetics are related to genotoxicities, sister chromatid exchange, and might be related to spontaneous abortion, stillbirth or birth defects. Some of the anti-neoplastic drugs such as Busulfan, Chlorambucil, cyclophosphamide, melphalan are Group 1 carcinogens. They could cause nausea, pruritus, or decreasing leukocytes or platelets. Other miscellaneous chemical agents are heavy metals such as elementary mercury or lead and organic solvents such as toluene, xylene and acetone. Although some of these chemical agents including EO gas have occasionally exceeded to permissible level, air levels of most above chemicals in Korean hospitals were relatively low. However, we have to make every effort to reduce the exposure level of these chemicals.