Over 30% of breast cancers are diagnosed after age 70. The incidence of breast cancer in the elderly has increased since 1960. Risk factors for breast cancer are a medical history without pregnancy, a first pregnancy after age 30 and the use of hormonal replacement therapy. The biology of breast cancer at advanced age indicates a relative slow, less aggressive and hormone dependent tumour growth. In spite of these favourable characteristics, the prognosis is not better than at middle age. Over 20% of older patients die from co-existing other diseases within 5 years after the diagnosis of breast cancer. This comorbidity, mostly cardiovascular or pulmonary, affects the possibilities and the outcome of treatment. Treatment of the primary tumour is performed according to the same guidelines as in younger patients. Indication exists for hormonal adjuvant treatment with tamoxifen in patients with oestrogen receptor positive tumours. Hormonal treatment is the treatment of choice in metastatic disease. Chemotherapy is given in patients with oestrogen receptor negative tumours and in patients with progressive hepatic or pulmonary metastases.