Antinuclear antibody(ANA) and rheumatoid factor(RF) in the sera of 191 coal workers pneumoconiosis(CWP) patients, 65 healthy coal workers, and 52 non-mining controls were examined by the categories of CWP, age, duration of exposure, smoking and drinking habit. Indirect fluorescent antibody technique for ANA and latex agglutination method for RF were applied for detection. ANA was positive in 24.3% of CWP patients, 10.8% of healthy coal workers and 11.5% of non-mining controls. RF was positive in 36.5 % of CWP patients, 13.8 % of healthy coal workers and 9.6 % of non-mining controls.