The national breast cancer screening programme in Luxembourg, the Mammography Programme (MP), was launched in 1992. Its primary goal was to set up an organised breast cancer screening with biennial invitation-reinvitation of women 50 -64 years, 2-view mammography, technical quality assurance, double-reading procedures and close monitoring of performance. In 1994, the decision was taken by health authorities to only reimburse screening mammograms done within the MP. We evaluated the performance of 3 screening rounds that took place in 1992-1997. In 1992, 4,815 women had opportunistic screening and 4,790 attended the MP. In 1997, 861 women had opportunistic screening and 8,603 attended the MP. In 1997, the participation rate in the MP reached 50%. The referral rate in the MP was 10% for initial screening and 5% for subsequent screening. Echographic examinations accounted for 71% of referrals. Per 1,000 screened women, biopsy and cancer rates were 18.0 and 8.0 for initial screening and 10.3 and 5.8 for subsequent screening. Twenty-one percent of the breast cancers diagnosed in screened women were interval cancers. The age-adjusted proportion of tumours >20 mm was 56.1% before 1992, 45.1% for women not (yet) screened by the MP, 27.0% for interval cancers, 26.6% for initial screening and 12.0% for subsequent screenings. Tumour size distribution was similar to that observed in the Dutch Breast Cancer Screening Programme, 1990 -1993, except that in the latter programme, no difference was observed between initial and subsequent screening. The Luxembourg experience shows that in a liberal health care system, a policy of organising the screening process by reimbursing only those mammograms done within the context of the organised screening programme can drastically reduce opportunistic screening. Further efforts in the Mammography Programme will aim at increasing participation and look at ways to decrease referrals to echography.