OBJECTIVE Primary radiation therapy following breast-conserving surgery has been an accepted alternative to mastectomy in Europe and North America for many years. In Australia, however, the history of breast conservation for early invasive breast cancer is much shorter. The purpose of this study was to evaluate the results of breast conservation in a state-wide Australian radiotherapy service. METHODS Between January 1982 and December 1989, 512 patients were treated with primary radiation therapy after breast conserving surgery. This analysis is based on a review of these patients, all of whom had Stage I or II breast cancer. RESULTS With a median follow-up of 50 months, the 5-year actuarial rate of overall survival was 84% and disease-free survival was 80%. There have been 22 isolated local recurrences in the breast. The time to an isolated breast recurrence ranged from 12 to 83 months (median, 26 months). The 5-year actuarial rate of an isolated breast recurrence was 4%. The recurrence rate was higher for patients with involved margins (15% vs. 2%, p < 0.01). Local recurrence was also more likely in the presence of extensive ductal carcinoma in situ (DCIS), as opposed to no extensive DCIS (10% vs. 2%, p < 0.01). CONCLUSIONS These results affirm that primary radiation therapy after breast conserving surgery in Queensland, has been given with a low rate of local recurrence, comparable to that obtained in other centers.