Breast conserving surgery and irradiation is now accepted as preferable treatment method for the patients with stage I and II breast cancer. Our institution activated team approach for breast conservation 1991 and treated on hundred and forty patients during the next three years. PURPOSE: To present our early experience with eligibility criteria, treatment techniques, and the morbidities of primary radiotherapy. MATERIALS AND METHODS: Sixty four patients with early stage breast cancer who received breast conserving treatment between January 1991 and December 1992 were evaluated. All patients received partial mastectomy(wide excision to quadrantectomy) and axillary node dissection followed by radiotherapy. Total dose of 4500-5040 cGy in 5-5 1/2 weeks was given to entire involved breast and boost dose of 1000-2000 cGy in 1-2 weeks was given to the primary tumor site. Linac 4 MV X-ray was used for breast irradiation and electron beam was used for boost. Thirty five patients received chemotherapy before or after radiotherapy. Patients characteristics, treatment techniques, and treatment related morbidities were analyzed. RESULTS: Age distribution was ranged from 23 to 59 year old with median age of 40. Twenty-seven patients had T1 lesions and 34 patients had T2 lesions. In three patients, pathologic diagnosis was ductal carcinoma in situ. Thirty-seven patients were N0 and 27 patients were N1. There were three recurrences, one in the breast and two distant metastases during follow-up period(6-30 months, median 14 months). Only one breast recurrence occurred at undetected separate lesion with microcalcifications on initial mammogram. There was no serious side reaction which interrupted treatment courses or severe late complication. Only one symptomatic radiation pneumonitis and one asymptomatic radiation peumonitis were noted. CONCLUSIONS: Conservative surgery and primary radiotherapy for early breast cancer in proven to be safe and comfortable treatment method without any major complication. Long-term follow up is needed to evaluate our treatment results in terms of loco-regional control rate, survival rate, and cosmetic effect.