PURPOSE: To evaluate treatment results of breast conserving surgery and radiation therapy including survival rates, patterns of failure, and complication and to analyze prognostic factors. MATERIALS AND METHODS: Retrospective analysis was carried out for 111 (112 cases) consecutive patients with breast cancer treated by radiation therapy after breast conserving surgery from October 1994 to April 1997. The median follow up was 45 months (range 10~66). AJCC staging was as follows: 16 cases (14%) for ductal carcinoma in situ, 46 cases (41%) for stage I, 33 cases (30%) for stage IIa, and 17 cases (15%) for stage IIb. Radiation therapy after breast conserving surgery was delivered to whole breast with 50.4 Gy and additional 10 Gy electron beam boost to tumor bed. Adjuvant CMF or CAF chemotherapy was performed in 61 patients. RESULTS: Overall three- and five-year survivals were 99% and 95%, and progression-free survival were 93%, 87%, respectively. Treatment failure occurred in 11 cases (10%); loco-regional recur rence in six; distant metastasis in five. Univariate analysis showed prognostic factor affecting survival was only T-stage. Acute radiation dermatitis were found in five cases (4%), and chronic complications were found in five (4%); one case with amputation of nipple, two cases with lymphedema requiring rehabilitation therapy and two cases with symptomatic radiation pneu monitis requiring steroid therapy. CONCLUSION: Breast conserving therapy of early breast cancer including ductal carcinoma in situ showed high survival rates and low complications, and T stage was prognostic factor for survival. But further follow-up should be needed.