BACKGROUND: Substantial regional heterogeneity in the provision of cancer prevention and management services results from the decentralised Swiss healthcare system. MATERIALS AND METHODS: Breast cancer mortality trends between 1980 and 2002 were compared in two French- and in two German-speaking female populations of Switzerland, aged 55-74 years, characterised by different access to, and use of, mammography screening. RESULTS: Since the early 1990s, a 30% fall was observed in the French-speaking regions of Vaud and Geneva, where mammography screening is widespread, with no decline in the German-speaking areas of Basel and Zurich. CONCLUSION: Modification in breast cancer diagnosis and management in selected regions of Switzerland is urgently needed. [Authors]