The National Institute for Occupational Safety and Health's (NIOSH) Health Hazard Evaluation and Technical Assistance (HETA) program responds to approximately 400 requests per year from employers, employees, employee representatives, other Federal agencies, and State and local agencies to examine suspected hazards in the workplace. The typical HETA response to a request for assistance results in an evaluation of whether chemical, physical, biological, or other agents are hazardous as used or found in the workplace followed by the development of recommendations for control procedures, improved work practices, and medical programs to reduce exposure levels and prevent adverse health effects. The results of individual evaluations may trigger wider studies of similar exposures in other settings, or may stimulate recommendations for implementation or modification of health standards. Requests received by the HETA program tend to reflect emerging occupational problems. More than 8,000 evaluations have been completed since the inception of the HETA program in 1972 on hazards such as chemical exposures, indoor air quality, ergonomics and noise-induced hearing loss. Noise-induced hearing loss is one of the most prevalent occupational health hazards facing American workers today. Approximately 30 million people are exposed to hazardous levels of noise at their work sites and an additional 9 million are at risk from other substances such as solvents and metals. While noise-induced hearing loss is irreversible, it is preventable and its risk can be reduced with the application of noise controls and occupational hearing loss prevention programs. When evaluating noise during an Health Hazard Evaluation (HHE), staff may monitor noise exposures, survey worker medical information, conduct worker audiometric evaluations, assess worker use of hearing loss protection devices, and evaluate hearing loss prevention policies and standards. NIOSH researchers present written reports detailing the results of their evaluations to help companies assess workers exposure to noise, evaluate and plan noise controls, and develop employee education programs on hearing loss prevention. This document presents summaries of the HHEs related to noise conducted from 1986-1997. The summaries are organized by industry. In several cases noise exposure was just one of many exposures that NIOSH researchers investigated at the work site.