Background.Previous cohort studies have found an elevated risk of lung cancer among rock and slag wool (RSW) production workers. The aim of the present study was to investigate the risk of lung cancer associated with exposure to RSW while controlling for other occupational exposures and tobacco smoking.Methods.Since 1971, a total of 196 lung cancer cases occurred among men who worked in seven plants in Denmark, Norway, Sweden, and Germany, with start of production between 1937 and 1950. We obtained information on occupational history and extra-occupational factors from either the subject or the next of kin for 133 cases and 513 matched controls. We assessed occupational exposure on the basis of interview data combined with information from expert panels set up in each factory.Results.For cumulative exposure to RSW assessed with a 15-year lag, the smoking-adjusted odds ratios in the second, third, and fourth quartiles of exposure were 1.3 (95% confidence interval [CI] = 0.7–2.3), 1.0 (CI = 0.5–1.9), and 0.7 (CI = 0.3–1.3). Similar results were obtained when we included only those workers employed for more than 1 year, when we included other indicators of RSW exposure, and after control for co-exposures.Conclusions.This study provides no evidence of a carcinogenic effect on the lung of rock and slag wool under exposure circumstances in the production industry during the last four to five decades.