Malignant tumours account for about 20% of the mortality of our population. Their epidemiology deserves therefore, no doubt, greater attention than it had so far. In the context of epidemiology of non-communicable diseases which is still not sufficiently appreciated in this country, it is desirable to pay due attention also to risk factors of malignant processes. It is a classical example of essential multidisciplinary collaboration and of comprehensive approach at least of the clinician working with the patient, the hygienist who describes truthfully the exposure to risk factors, and the epidemiologist who will design the most suitable type of study and method of evaluation of the assembled results. Patience and systematic work, frequently extending over many years, is a condition sine qua non.