A case-control study in an industrialized area of eastern Pennsylvania involving interviews with the next of kin of 335 men who died of lung cancer and of 332 controls who died of other causes revealed a significantly increased risk associated with employment in the steel industry, the area's major employer. The excess was primarily among long-term employees, particularly those who began work before 1935. Adjusted for cigarette smoking, the odds ratio associated with career employment was 1.8 (p = 0.01, 95% confidence interval, 1.2, 2.8). The increase was higher among steel workers who worked in foundry operations, but was seen for broad categories of jobs within the industry. No significant associations were found for other industries, although a 60% increase (p = 0.27, 95% confidence interval, 0.7, 3.7) was noted for zinc smelter workers employed at least 15 years. The findings help clarify the role of occupation as a risk factor for lung cancer in the area, and suggest that exposures in the steel industry contribute to an extent greater than previously recognized.