The characteristics of chronically dusty longwall coal mines in the United States (US) were examined. Data were collected on all US longwall mines for fiscal years 1982 through 1987 to determine which were out of compliance with the coal dust standard, 2.0mg/m3. Mines that were out of compliance with the standard for at least 3 of the past 4 years were considered to be chronically dusty. Data on the physical characteristics of longwall panels in mines with active longwall sections were obtained from annual census data published in industry trade publications. A census of mines currently using diesel powered equipment was obtained. Nineteen longwall mines were found to be chronically dusty. Nine were in the West, three in northern Appalachia, and seven in the southern Appalachian region. Chronically dusty mines were somewhat more likely to use diesel equipment than nondusty mines. They were significantly more likely to use two entries for their longwall panels. The length, width, and cutting height of chronically dusty longwall panels were slightly, but not significantly larger than those of nondusty panels. Dust exposures at continuous miner sections of the dusty mines were also elevated. The author concludes that longwall mines in the western US have the poorest performance. Chronically elevated dust concentrations are associated with the use of two entries. Excessive dust exposures are not limited to longwall panels.