A series of 178 patients in whom carcinoma of the breast was associated with pregnancy has been analysed. In 121 patients the carcinoma was diagnosed during pregnancy (CP group) and in 57 patients the pregnancy occurred subsequent to definitive treatment for primary breast carcinoma (SP group). Patients presented with more advanced disease in the CP group, 72 per cent being axillary node positive. Only 37 per cent of the 121 patients survived 5 years, although 79 per cent of the node negative patients survived 5 years. Survival was not affected by age, nor by the phase of pregnancy during which the carcinoma was diagnosed or treated. The majority of pregnancies (79 per cent) ended in the delivery of a normal child. The 5 year survival of the 57 patients in the SP group was 69 per cent. However only 26 per cent of the patients who had positive nodes at the time of primary surgery were disease free 10 years later. This fact should be borne in mind when considering the continuation of the pregnancy.