Compliance and coverage are supposed to be indicators of effectiveness in screening activities. Yet effectiveness is a necessary but not sufficient condition for a screening programme: adverse effects are intrinsic to screening practice; to persuade to comply to screening programme should imply that the advantages overwhelm the disadvantages; if at community level the balance is in favour of the screening, it is not possible to predict the weight for each individual of any potential harms. To accomplish individual values is fundamental from ethical point of view: we must avoid non responsible participation or uninformed refusal, through a reliable information on screening benefits and harms to the invited population. Therefore the concept of compliance should be abandon: "participation" should be used instead. The consequence of a different approach to participation in screening evaluation should be appreciated: new indicators and standards have to be defined. The following ones are proposed: prevalence of informed target population; prevalence of consent to invitation within the informed population; ratio consent/refusal to invitation; prevalence of participation in the invited group. It is unrealistic to expect an informed participation, to screening programme, from all population but incorporation of patient values and preferences is seen as the next frontier in attempts to devise valid practice guidelines. Research is needed to develop instrument on risk communication and informed consent, taking into account the current organisation of screening programs.