One-hundred-and-seventy-one patients with invasive lobular carcinomas have been matched with 342 patients with non-lobular invasive carcinomas for lymph node stage, tumour differentiation and patient age on a one to two basis. The two groups were investigated for differences in prognostic factors, survival, disease-free interval, metastatic patterns, receptor status, response to endocrine therapy after distant metastases and bilateral cancer rates. Patients with lobular carcinomas survived significantly longer than patients with carcinomas of no specific type, particularly in survival from the time of diagnosis of distant metastases; lobular carcinomas more often responded to endocrine treatment for systemic disease. Lobular cancers had a significantly higher rate of local recurrence, particularly after treatment by excision and breast irradiation. No differences were found between the two groups with respect to regional or distant recurrence rates, distant organ involvement patterns, distant metastatic free intervals and receptor status. Bilateral cancer was more frequent in patients with lobular carcinoma.