The relationship between simple coal workers' pneumoconiosis (CWP) and lung cancer mortality was examined. A cohort of 317 United States male lung cancer deaths was selected from among four NIOSH coal miner mortality data sets. The data sets were: the Appalachian cohort; National Coal Study, Round Number 1 cohort; the Charleston/Beckley cohort; and the National Coal Worker's Autopsy Study. A 1:1 matched case analysis by age at death was used to study the lung cancer mortality risk of CWP and cigarette smoking. A 2:1 matched case analysis by age at death and smoking status was utilized to examine the lung cancer risk of CWP independent of cigarette smoking. In the 1:1 match, the odds ratio (OR) risk of lung cancer mortality for smokers compared to nonsmokers was 4.56. This risk was highest in persons with normal ventilation function (OR, 23.63). Neither simple nor complicated CWP were statistically significant risk factors for lung cancer mortality; the OR was 0.99 for simple CWP and 1.79 for complicated CWP. In the 2:1 match, smoking cigarettes for 30 or more years doubled the lung cancer mortality risk. Simple CWP presented no risk of lung cancer (OR, 1.00). Complicated CWP showed an elevated, but statistically insignificant risk (OR, 2.31). The author concludes that CWP by itself or in combination with cigarette smoking or lung function impairment does not cause an increased risk of mortality from lung cancer.