The relationship to survival after first recurrence of oestrogen receptor (ER), nodal status and TNM stage at diagnosis, and treatment for advanced disease was studied in 457 females whose primary breast cancer was diagnosed in 1975 to 1981. Receptor concentration was the most important predictor of post-recurrence survival, with some additional information conveyed by nodal status. ER predicted survival after recurrence independently of nodal status, clinical stage or mode of therapy. Response to endocrine therapy is only a facet of the generally favourable prognosis of ER positive patients, rather than the sole explanation.