The importance of epidemiology in the study of causes of bone tumours. 
Research into the causes of disease in human populations makes use of epidemiological methods for recognizing avoidable risk factors which may be active prior to the occurrence of malignant tumours.  With the exception of the risks or irradiation, the aetiology of bone tumours remains unclear, and it is particularly striking that in the literature to date and in a survey of research currently in progress there are no epidemiological studies which involve other than radiation-exposed populations.  This is the reason why it has only been possible to obtain initial suggestions of potential areas of risk from ecologic correlations based on the evaluation of mortality and morbidity rates with respect to environmental factors.  Several results obtained from systematic comparisons of mortality in the countries of the world and two correlative relationships are reported, and the difficulties in interpreting the results are discussed.  Population-based registration of bone tumours and case-control studies based on registries are recommended.