Characteristics of primary breast tumours were related to the extent of dissemination, the anatomical location of metastases, and the rate of progression in 863 patients with recurrent breast cancer. The following features were examined: tumour laterality, location within the breast, size, invasion of skin or fascia, presence of residual cancer tissue (RCT) in the mastectomy specimen, and number of positive lymph nodes. Increasing tumour size, increasing number of nodes, and the presence of local invasion and RCT were all associated with a short duration of survival both from initial diagnosis and from first recurrence. None of the factors were related to either the extent of dissemination or the rate of progression. Patients who had their primary tumours located in the medial or central part of the breast had an increased incidence of mediastinal and pleural recurrences respectively. Primary tumours greater than 5 cm, invasion of skin or fascia, and presence of RCT were all associated with an increased incidence of local recurrences. In addition, both RCT and fascial invasion were associated with increased occurrence of brain metastases. Most differences were explainable on the basis of local and regional lymphodynamics. Since the status of the features examined here all vary with time from tumour inception, it is suggested that the impact on prognosis is related to variations in tumour age from inception to primary diagnosis rather than to qualitative biological differences.