PURPOSE: Regional disparities in breast cancer outcomes have been reported in Switzerland. The purpose of this study is to investigate geographic variation in early diagnosis and management of breast cancer. METHODS: We used data from a representative sample of 4820 women diagnosed with invasive breast cancer between January 1, 2003 and December 31, 2005 identified by seven Swiss population based cancer registries. We collected retrospectively detailed information on mode of detection, tumor characteristics and treatments. Differences across geographic regions were tested for statistical significance using chi-square tests and uni- and multivariate logistic regression. RESULTS: Considerable disparities in early detection and management of early breast cancer were found across regions. In particular, the proportion of early detected cancer varied from 43% in Valais to 27% in St. Gallen-Appenzell. Mastectomy rates varied from 24% in Geneva to 38% in St. Gallen-Appenzell and Grisons-Glarus. Higher reconstruction rates were observed in regions with lower rates of mastectomy. The use of sentinel node procedure in patients with nodal negative disease was high in Geneva and low in Eastern Switzerland. Differences in compliance with recommendations on the use of endocrine therapy and chemotherapy were less pronounced but statistically significant. CONCLUSIONS: This analysis shows considerable geographic variation in breast cancer care in a health system characterized by high expenditures, universal access to services and high decentralization. Further study into the causes and effects of this variation on short- and long term patient outcomes is needed.