We have examined the clinical records fo 1238 patients with operable breast cancer to identify the sites of metastatic disease. Infiltrating ductal carcinoma (IDC) recurred more commonly in lung (P < 0.05), pleura (P < 0.05) and brain (P < 0.05), while infiltrating lobular carcinoma (ILC) more commonly metastasised to the bone marrow (P < 0.01) and peritoneum (P < 0.01). Bone involvement as the initial presentation of distant metastatic disease occurred in over 50% of women with ILC, significantly more commonly than in those with IDC (34%, P < 0.01). Survival was similar for the two groups, both from time of diagnosis and from time of development of distant metastases.