Purpose: A retrospective chart review was conducted to determine if the time interval from conservative breast surgery to breast irradiation (surgery – radiotherapy interval) in early stage node negative breast cancer had any detrimental effect on recurrence rates. Materials and Methods: There were 566 patients with T1-T3, N0 breast cancer treated with breast conserving surgery and breast irradiation and without adjuvant systemic treatment between 1985 and 1992. The surgery – radiotherapy intervals used for analysis were: 0-8 weeks (201 patients), >8-12 weeks (233 patients), >12-16 weeks (91 patients) and >16 weeks (41 patients). Kaplan-Meir estimates of time to local-recurrence, disease-free survival, distant-free survival, cause-specific survival and overall survival rates were calculated. Results: Median follow-up was 17.4 years. Patients in all 4 time intervals were similar in terms of patient characteristics and pathologic features. There was no statistically significant difference between the 4 time groups in local-recurrence (p=0.67) or disease-free survival (p=0.45). The local recurrence rate at 5, 10 and 15 years was 4.9%, 11.5% and 15.0% respectively. The distant-disease relapse rate at 5, 10 and 15 years was 10.6%, 15.4% and 18.5% respectively. The disease-free failure rate at 5, 10 and 15 years was 20%, 32.3% and 39.8% respectively. Cause-specific survival at 5, 10 and 15 years was 92%, 84.6 % and 79.8% respectively. The overall survival at 5, 10 and 15 years was 89.3%, 79.2% and 66.9%. Conclusion: Surgery-radiotherapy intervals up to 16 weeks from definitive breast surgery are not associated with any increased risk of recurrence in early stage node negative breast cancer. There is a steady local recurrence rate of 1% per year with adjuvant radiation alone.