The incidence of lung cancer among 280 silicotic men working in the ceramics industry and notified to the Swedish Silicosis Registry has been investigated. During the study period 1958-83, the risk of lung cancer (nine cases) was double that expected based on national rates. There was no increased incidence of cancer at any other site. The results are in agreement with those of both animal and epidemiological studies of quartz exposure and point to an increased risk of lung cancer, especially among silicotics. Various possible explanations of this increased risk are discussed, but further studies are required.