Lung specimens from 39 nickel refinery workers autopsied during the period from 1978 to 1984 were analyzed for nickel. Fifteen of the workers were employed in the Roasting and Smelting Department, where exposure to nickel was predominantly in the form of nickel-copper oxides, Ni3S2 and metallic dust. The remaining 24 men worked in the Electrolysis Department. Exposure in this group was considered to be mostly to the water-soluble compounds, NiSO4 and NiCl2, but also to a lesser degree to water-insoluble nickel compounds such as nickel-copper oxides and sulphides. The arithmetic mean +/- SD for nickel concentration in lung tissues expressed in micrograms g-1 dry wt for the 39 workers was 150 +/- 280. In the workers employed in the Roasting and Smelting Department, the average nickel concentration was 330 +/- 380; for those who worked in the Electrolysis Department it was 34 +/- 48. Lung tissue from 16 autopsied persons not connected with the refinery had an average nickel concentration of 0.76 +/- 0.39. Statistical analysis based on log-normal distributions of the measured nickel concentrations allowed three major conclusions to be formulated: (1) nickel refinery workers exhibit elevated nickel levels in lung tissues at autopsy; (2) workers of the Electrolysis Department and the Roasting Smelting Department constitute distinct groups with respect to the accumulation of nickel in lung tissue; (3) workers who were diagnosed to have lung cancer had the same lung nickel concentrations at autopsy as those who died of other causes.