As many breast cancer cases are detected outside mammographic screening, a multidisciplinary quality management (QuaMaDi) project involving gynaecologists, double reading by radiologists. and centralised assessment, documentation, evaluation and feedback was implemented into routine breast cancer diagnosis in part of Schleswig-Holstein (Germany) with a population of 365,000 women. A cohort of 59,514 patients eligible for diagnostic mammography was examined from May 2001 to December 2005 and quality indicators, breast cancer incidence and tumour stage distribution were analysed. A total of 102,744 diagnostic processes were initiated, for 23.8% of which (24,470) a third expert reading at the reference centre was performed. Further assessment was recommended for 6.3% (6442) of all patients. In total, 1056 breast cancer cases were diagnosed (10.3 per 1000 examinations). Patients of the QuaMaDi project had a higher proportion of 'in situ' and T1 tumours (62.6% vs Schleswig-Holstein: 48.6%), showing that the implementation of high standards in routine diagnostic mammography can improve the quality of breast cancer diagnosis and care.