[en] Based upon the tabulated values of the European Radon Study, the relationship between lung cancer risk and radon exposure is re-investigated. The evaluation of the relative risk according to exposure categories shows clear deviations from linearity without threshold. Calculations of the odds ratios for the individual exposure categories based on the tabulated numbers of cases and controls show large systematic deviations from a linear exposure-risk relationship in the six investigated diagnosis and smoking groups. A dichotomic partition of exposures at 100 Bq/m³ reveals no increased risk for the upper categories. For the again and again published estimations of the yearly expected numbers of new cases of lung cancer attributable to radon exposure, and for downward corrections of the reference values for the mitigation of radon levels, the European Radon study in its present form is therefore not a sound basis. (orig.)