For almost all of the sites of most common cancers, particularly the lung, colo-rectum and cervix, relatively inexpensiveand reliable tests have been available for some time. Advances in imaging techniques now allow identification ofearly tumours in many other organs, including those that are normally associated with a very poor prognosis. Inaddition, increasing knowledge of the risk factors for cancer development in different organs imply more effectivescreening for early malignancies in high risk populations and the associated increase in the predictive value shouldmean that early intervention will result in a marked decrease in the mortality and morbidity due to a wide range ofmajor cancers. However, there are many difficulties which remain to be overcome, especially in the psychosocialarea. Problems with overdiagnosis and distinction of lesions most likely to actually give rise to cancers also requireespecial attention for the full promise of screening to be realised. In addition, choice of the most appropriate approachwill require an in depth understanding of cultural factors impacting on screening behaviour and it is of paramountimportance that both physicians and the public at large be fully aware of pitfalls and potential benefits. Thus researchneeds to be concentrated on effective education approaches as well as how to increase practical sensitivity and specificityof individual tests and determine the best follow-up for individuals testing positive.