Health care workers encounter many physical hazards in hospitals, including ionizing radiation, noise, and heat. Ionizing radiation is used in hospitals for diagnostic radiology, therapeutic radiology, dermatology, nuclear medicine, and in radiopharmaceutical laboratories. Radiation hazards may also exist in areas where radioactive materials are stored or discarded. Occupational exposure to ionizing radiation can lead to erythema or radiodermatitis. Ionizing radiation can cause gene mutation and chromosomal alteration. Other somatic effects that result from irradiation include several types of cancers (myelogenous leukemia, bone cancer, skin cancer, thyroid cancer, etc.), cataracts, aplastic anemia, and sterility. The chief methods for reducing doses of ionizing radiation from external X-rays and gamma rays are to limit the time of exposure, increase the distance from the source of the exposure, shield the source with protective materials, and avoid unnecessary exposures. Improved equipment, knowledge, and reduced exposures can greatly reduce the risk of radiation exposure for workers. Many work areas in hospitals were identified as noisy enough to decrease productivity. Noise may trigger changes in cardiovascular, endocrine, neurological, and other physiological functions. Working in high-noise areas makes it difficult for workers to communicate among themselves or to concentrate on critical job functions. Many places in hospitals including the laundry, boiler room, and kitchen may be hot during the summer months, especially in older facilities that have inadequate ventilation and cooling systems. Health care workers should pay attention to health disorders caused by physical factors to protect themselves against many hazards in hospitals.