Information on the health effects of, and exposure to, ultrasound was reviewed to assess the potential occupational hazards associated with medical, industrial, and scientific uses of ultrasound. Topics included the biological effects of exposure, dose response relationships, ultrasonic equipment, and occupational exposures. Estimates of exposure levels were made. The authors conclude that the threshold dose for biological effects in animals is about 25 joules (J) per square centimeter (cm2), while the human threshold dose is about 50J/cm2; corresponding intensities are 0.05 and 0.1 watt (W) per cm2. Most commercial ultrasound equipment produces output intensities below 10 milliwatts/cm2 at the transducer face. At common operator positions, these are below 1 microwatt/cm2. Except for special exposure conditions, airborne ultrasound is not expected to be a hazard. Direct contact with liquidborne or solidborne ultrasound may present a hazard. Aerosols, noise, and vibration may present secondary hazards of ultrasound in industrial settings. The authors recommend the following: analysis of potential for exposure; determination of work practices, engineering, and administrative controls; measurement of ultrasonic intensities in work areas; evaluation of health effects of secondary hazards; evaluation of data from diagnostic and therapeutic ultrasound equipment manufacturers; review of hazards associated with high intensity, low frequency sources; and development of an occupational hazard assessment.