The prognostic significance of local relapse after conservative treatment of early stage breast cancer has been controversial. To determine the prognostic value of breast relapse occurrence and the factors predisposing to local failure, we analysed the results obtained in a series of 324 patients conservatively treated for breast invasive carcinomas of 2 cm or less. All patients were treated by tumorectomy and axillary dissection, radiation therapy, and adjuvant medical treatment in 85 of 109 patients with involved nodes. The overall 5-yr survival rate was 91.5%. The actuarial 5-yr local control rate was 91.9%. Local relapses occurred in 25 patients. In these patients, the overall 5-yr survival rate was significantly decreased as compared to that of patients without local relapse (76.9% versus 93.4%, P less than 0.001). Recurrence in the breast within 2 yr of initial treatment of severely affected the risk of metastasis occurrence as compared to later relapses (metastasis-free survival rate of 14.3% versus 63.9% at 3-yr from local relapse, P less than 0.01). Local relapse occurred more frequently in premenopausal patients, in patients with low bodymass index, and in patients with small breast size. Local control was not significantly affected by age, tumor size or node involvement. We conclude that the occurrence of a breast relapse after a local conservative treatment has a negative significance and is predictive of a high risk of distant metastasis development, especially when local relapse occurred within 2 yr of initial treatment. There is a need to determine individual factors that could allow discrimination of patients with a high probability of local relapse and subsequent metastasis.