An overview of the Coal Workers Health Surveillance Program was conducted. Under the Coal Mine Health and Safety Act of 1969, miners employed since 1970 were required to have a chest radiograph taken just after employment and again 3 years later. Underground coal miners were therefore eligible to volunteer for radiographs at intervals of less than 5 years. In 1970 this labor force numbered 120,000; by 1980 it had leveled off at 150,000. In Rounds 1, 2, and 3 of x-rays, miners under 30 years of age represented 37%, 58%, and 49%, respectively. In each round the largest regional distribution percentage was from Appalachia, with 92% in Round 1 decreasing to 82% in Round 3. From 1970 through 1980 a total of 9800 miners were eligible for transfer to low dust work areas (4100, 2800, and 2900 for the successive rounds). About 1700 of those eligible were actually transferred. Within each round the presence of Coal Worker's Pneumoconiosis increased with tenure; the highest overall prevalence was seen in Round 2 at 29% for 35 years experience. Data indicate that new miners participate in the program because they are required to do so, but that they do not continue participating.