The prognostic role of axillary lymph node status, progesterone receptor (PgR) status, age of the patient at operation, oestrogen receptor (ER) status and tumour diameter was studied in 443 breast cancer patients treated by modified radical mastectomy. Logistic and proportional hazard regression analyses were used to estimate the prognosis from the time of operation up to 60 months. We also estimated the prognosis from 36 to 60 months for those who had survived 36 months (conditional analysis). PgR and age gave significant information in each node class, old age and PgR negativity being disadvantages. PgR status relative to node status was more important for estimating early (24 months) prognosis, while age was of more importance later (60 months). Node status and age were the only variables giving significant information in the conditional analyses. It is thus of importance to consider the time dependency of the prognostic variables when predicting survival in breast cancer patients. No effect was found for ER status or tumour diameter.