Biomarkers are measured in the management of breast cancer patients for the following purposes: (1) early detection, (2) monitoring of advanced breast cancer patients, (3) prediction of prognosis, and (4) prediction of therapeutic response. Summarized results investigated by the Study Group of the Japanese Breast Cancer Society in 2001 concerning the present status of tumor marker measurement in Japan and usefulness of tumor markers for the evaluation for therapeutic response are presented. Significance of two prognostic markers, vessel invasion and HER2 status were discussed at the 9th St Gallen International Consensus Meeting in 2005. Current status, clinical significance, problems and future directions on predictive markers for response to endocrine therapy and cytotoxic chemotherapy are also discussed.