Health care is a labour intensive industry and, in most countries, health care workers (HCWs) are fast growing sector of the workforce. Variety of occupational hazard, such as biological, ergonomical, chemical, physical and psychological factors, have been reported in HCWs. Major occupational infectious diseases in HCWs are blood-borne pathogens such as HIV, hepatitis B and hepatitis C, and airborne pathogens such as tuberculosis, and a wide variety of respiratory viruses. Most common occupational musculoskeletal disorder (MSD) in HCWs are low back pain and related diseases. One of the most prevalent ergonomical risk factor of low back pain is moving the patients or changing the patients' position. Important carcinogenic chemicals in HCWs are formaldehyde, ethylene oxide and anticancer drugs, which have been reported reported to be cause of occupational lymphohematopoietic cancer. Glutaraldehyde and latex glove can cause allergic asthma and contact dermatitis. Physical hazard such as ionizing radiation and noise also should be considered for HCWs's occupational health. Because, HCWs comprise a wide range of professional, technical and support personnel, the organizational factor might affect to job stress. In addition to organizational factors, the shift work and night work is serious health problem of HCWs. Theses risk factors can affect to chronic underlying disorder.