The prognostic significance of local relapse after conservative treatment of early stage breast carcinoma has been controversial. To determine the incidence and the prognostic value of a breast relapse, we analyzed the results obtained in a series of patients with pT1pN0 presentation of breast carcinoma treated conservatively without adjuvant medical treatment. From 1976 to 1986, 202 patients with invasive breast carcinoma of less than 2 cm without lymph node involvement were treated with surgery and radiation therapy. The overall survival rate was 97.2% at 5 years. Locoregional relapses occurred in 16 patients (7.9%). In these patients, the overall survival rate was significantly decreased as compared to that of patients without local relapse (87.5% versus 98.3% at 5 years, p less than 0.001). The probability of remaining metastasis-free was also significantly decreased (80.2% vs 91.3%, p less than 0.001). Most relapses (94%) appeared at or close to the primary site. Salvage local treatment was possible in 14/16 patients (87.5%). Age, menopausal status, size and site of primary tumor, histological grade, and boost technique did not influence significantly the risk of local relapse occurrence. We concluded that the occurrence of a breast relapse after a successful local conservative treatment is a pejorative prognostic factor predictive of a high risk of distant metastasis development. There is a need to individualize factors that could allow discrimination of patients with a high probability of local relapse and subsequent metastasis.