To check the question as to the prognostic significance of oestrogen and progesterone receptors in invasive breast cancer, the course of the disease was registered in 660 patients in the context of a retrospective study. These patients had been operated on with the objective of curing breast cancer between 1976 and 1984. A receptor analysis of these patients is available with regard to both receptor types. Positive progesterone receptors could be detected in 38%, positive oestrogen receptors in 70%. Values over 15 fmol/mg tissue protein were rated as positive. The proportion of oestrogen-receptor-positive tumours increased with the age of the patients. On the other hand, the progesterone receptor did not show this dependence. During analysis of the median receptor concentrations as well as of the progesterone combinations, a correlation between the axillary lymph node status and the hormone receptor status of the primary tumour could not be observed for the two receptor types. The survival time in relation to the oestrogen receptor status did not indicate any significant effect on survival time. On the other hand, the improvement of survival time depending on the positive progesterone receptor status was highly significant in statistical terms (p less than 0.001) especially in nodal-positive patients. Both patients with axillary lymph node metastases and positive progesterone status, compared with patients without lymph node invasion and a negative progesterone status, had the same survival rate.