This study evaluated the results of breast-conserving therapy (BCT). Nine hundred six patients who underwent BCT at our hospital between November 1987 and February 1998 were analyzed. The mean age was 48 years. According to the Union Internationale Contre le Cancer 1997 classification system, stages 0, I, IIA, IIB, IIIA, and IIIB were 37, 400, 344, 117, 7, and 1, respectively. Radiation therapy consisted of 50 Gy to the ipsilateral whole breast. Boost irradiation of 10 Gy was administered to 186 of 231 patients with close or positive margins. Nearly all patients received adjuvant chemohormonal therapy with tamoxifen and 5-fluorouracil or its derivatives for 2 years. The minimum and median follow-up periods were 18 and 52 months, respectively. The 5-year overall survival, cause-specific survival, local recurrence-free survival, and disease-free survival rates were 97.3%, 98.4%, 98.1%, and 91.5%, respectively. Local recurrence in preserved breast occurred in 20 patients 7 to 86 months after surgery. Multivariate analysis revealed that the most predictive factor for disease-free survival rates and distant failures was the number of pathologically positive lymph nodes (p< 0.0001), and that the factor for local failure was marginal status (p= 0.005). This study demonstrated that BCT was suitable for the treatment of early-stage breast cancer with its reasonable survival rates and acceptable toxicity.