The possibility of adverse respiratory health effects amongst coal miners in and at diesel-use mines has been investigated. Coal miners working in and at non-diesel-use mines served as matched controls. Differences in symptom prevalence and pulmonary function performance are documented. Several health indices have been related to a measure of diesel exposure. A preliminary characterization of the underground environment is shown. Underground miners in diesel-use mines reported more symptoms of cough and phlegm and had generally lower pulmonary function performance than matched controls. Similar trends were noted for surface workers at diesel-use mines compared with matched controls. Although a pattern consistent with small airways disease is shown, factors other than diesel exposure maybe responsible. Exposure time to diesel emissions for miners in this study is relatively short and measured concentrations are low. Based on present information, sufficient and consistent evidence does not exist allowing for the rejection of hypotheses of health equality between matched groups. A prudent public health stance dictates reservation of judgment pending prospective examinations and detailed environmental surveys.