Current regulations for U.S. underground coal mines, mandated by federal legislation in 1969 and amended in 1977, include provisions to prevent the occurrence of pneumoconiosis. However, in 2005 and 2006, clusters of rapidly progressing and potentially disabling pneumoconiosis were reported in certain geographic areas. In response to these reports, CDC's National Institute for Occupational Safety and Health (NIOSH) instituted field surveys conducted under the Enhanced Coal Workers' Health Surveillance Program (ECWHSP). This report describes the results of those surveys, which were conducted in three counties in eastern Kentucky (Knott, Letcher, and Pike) and four counties in southwestern Virginia (Buchanan, Dickenson, Tazewell, and Wise). A total of 37 cases of advanced pneumoconiosis (including four cases reported previously) were identified. Measures are needed to prevent further occurrence of this disease among underground coal miners.