The National Comprehensive Cancer Network (NCCN) recommends that patients with ductal carcinoma in situ (DCIS) and stage I/II invasive breast cancer receive radiation therapy following breast conserving surgery (BCS). The purpose for our study was to determine 1) the percentage of patients with DCIS and stage I/II breast cancer who received radiation therapy following BCS and 2) the clinical factors associated with the use of radiation. We retrospectively studied 606 patients treated between 2000 and 2007 with BCS for DCIS (n=104) and stage I/II breast cancer (n=502). Overall 93 percent of patients in our study received radiation therapy. We found that almost 85 percent and 95 percent of patients with DCIS and stage I/II breast cancer respectively received radiation therapy. Patients with invasive breast cancer who were less than 70 years of age and who received adjuvant systemic therapy were significantly more likely to receive radiation. The data from our study indicate that the use of radiation following BCS is high at our institution. Periodic review of treatment practices at local hospitals is valuable in assessing compliance with national guidelines and in improving quality of care.