The authors discuss the controversy about mass screening for breast cancer in order to assess the soundness of a nationwide expansion of such programmes. Mass screening is second best because of the failure of prevention, therapeutic progress or ability to target high risk populations, but its efficacy reducing mortality is not clearly demonstrated and the chances of one woman being saved from participating are very low. Detrimental side-effects such as anxiety, false alarms, unnecessary biopsies, overdiagnosis and overtreatment and deficiency of psychological approach are reported. On the other hand, mass screening may save lives and if no recent study can provide absolute proof of efficacy, inefficacy of systematic mammography cannot be proven either, even concerning 40 49 years old women. Moreover, screening trials have allowed an improvement in medical practice, especially concerning quality and dose in mammography and radiographer's performance. Many questions remain unanswered about mass screening for breast cancer and the best way to achieve it.