Between 1960 and 1984, 51 patients with Paget's disease of the nipple, with no concomitant palpable or radiological breast tumour, were treated at the Institut Curie. The diagnosis was made in all cases through a simple biopsy of the nipple and/or the areola. All slides were reviewed for the present study. 20/51 patients were treated conservatively, with external radiotherapy alone (17/20 pts), or limited surgery and radiotherapy (3/20 pts). The mean age was 54 years (range 40 to 80). The median follow-up was 7.5 years. No patients died of breast disease. Three local recurrences occurred and were treated by mastectomy. All were located in the nipple or areola and were Paget's disease without intraduct or invasive carcinoma. The actuarial probability of living 4.5 years free of disease when the breast is preserved with a good cosmetic result is 81%. 31/51 patients underwent mastectomy; 30 a modified mastectomy, 1 a simple mastectomy. The mean age was 66 years (range 55 to 90). Associated intraduct carcinoma was found in 30/31 microscopic examinations. No axillary node invasion was found after dissection of the axilla. In the group treated by surgery, the median follow-up was 5 years. No patient died of breast disease. No chest wall recurrence occurred. The 5 years disease-free survival rate was 87%. This retrospective non randomized study of 51 patients treated for Paget's disease of the nipple suggests that radiotherapy is a valuable alternative to mastectomy.(ABSTRACT TRUNCATED AT 250 WORDS)