Reported elsewhere in this issue (p 2056) is the experience of a local cancer detection center in finding cancer of the colon. This report, along with others concerning the routine periodic screening of the asymptomatic population, raises questions regarding the benefits derived from mass screening vs the costs. These expenses are reflected partially in public and private funds required to implement the programs. Heavily increased costs are also incurred by unneeded procedures precipitated by screening studies of limited specificity or sensitivity. When performed without selection, these examinations could include almost any laboratory study, since there is only a chance probability that a clinical indication exists.1Unsupervised self-examination of the breast has been implicated as a cause of emotionally traumatic costly hospitalizations.2Reconsideration of the benefits derived from annual Papanicolaou smears for every woman without selection has caused changes in practice in Great Britain.3,4Annual screening for thyroid