A historical cohort mortality study was conducted in three neighborhoods of Essex County, New Jersey, to investigate the mortality patterns of persons who had inhabited 45 homes documented to be contaminated by radon gas emanating from radium processing waste. Residency history and vital status were collected for 752 persons, comprising 91% of the subjects enumerated who had resided in the index homes for at least one year during the years 1923-1983. Standardized mortality ratios (SMR) were used to compare the death rates of the study group with the death rates of the United States and New Jersey. While there were no statistically significant excesses of lung cancer for the cohort or its subgroups, an elevated mortality rate for lung cancer was found for white males in the comparison of lung cancer mortality rates in the United States (SMR = 1.5, 95% confidence interval (CI) 0.7-2.7) and New Jersey (SMR = 1.7, 95% CI 0.8-3.2). No excess of lung cancer was observed in females or nonwhites. The small size of the cohort and the inability to collect smoking histories or complete occupational data limited the study. Nevertheless, the degree of excess lung cancer among white males was in agreement with both the attributable and relative risk estimates per unit of exposure derived for radon from mining studies.