Results are presented of a study of hearing loss in the underground coal mining industry. Hearing tests are given to 1,500 miners by NIOSH at eleven randomly selected coal mines in Kentucky, Pennsylvania, and West Virginia. Noise surveys are performed at the same mines by personnel of the Mining Enforcement and Safety Administration (previously of the U.S. Bureau of Mines). Hearing data are presented in groups based on noise exposure and job category. The data are also analyzed with respect to selected factors including recreational use of firearms and suspected otoscopic abnormalities. Statistical accuracy versus group sample size is discussed in an Appendix. Underground coal miners are found to have measureably worse hearing than the national average, but the degree of hearing loss is not as severe as among some other occupational groups. In light of the Bureau of Mines noise survey data, the hearing test results do not lend support to the notion that coal mine noise is inherently less hazardous than predicted from noise surveys because of its intermittent nature. Coal miners are found to have a higher than normal incidence of otoscopically observable ear abnormalities. Individual audiometric data are tabulated in an Appendix.