Résumé : A continuous series of 649 patients, treated by modified radical mastectomy for primary breast carcinoma, is analyzed after a median follow-up of 92 months. 'True isolated' locoregional recurrences (LR), defined as LR not preceded or followed by distant metastases within 6 weeks, appeared with a cumulative actuarial incidence rate of 6%, 14% and 19% after 1, 5 and 7 years respectively, whereas the respective figures for distant metastases (M1) were 10%, 37% and 48%. The main initial parameters, predicting both the LR-free and the M1-free interval, are presented by statistical analyses in the following order of importance: number of invaded lymph nodes in the axilla, tumor size (T) and histological grading of differentiation. The same factors also predicted the imminence of M1 once LR had occurred, as well as survival after LR. A higher incidence of M1 after LR was also correlated with estrogen-receptor negative tumors and with those LR occurring within one year after mastectomy. LR occurred at the chest wall (65%), in the sub-clavicular fossa (16%) and the axilla (6%); the remaining 13% occurred in two of the sites. There was a trend towards longer survival after chest wall recurrence than after LR recurrence at another site. Axillothoracic irradiations postmastectomy gave a lower rate of LR in 227 patients than did a regimen of 12 months adjuvant chemotherapy with irradiation restricted to the internal mammary lymph nodes in 120 subsequent patients: 17 vs 25% at 5 years (P = 0.03 when adjusted by initial nodal involvement and T-size). Total excision of LR (repeated if new LR occurred) gave better rates of local ultimate control and survival than other kinds of treatments, with or without adjuvant local or systemic therapy. LR is not always a sign of imminent generalized disease. Actuarial 5-year survival after LR is 26.2% overall whereas, if only 'true isolated' LR are considered, the survival is 37%.