This review focuses on four aspects of radiotherapy in the treatment of breast cancer. The most controversial area is the treatment of ductal carcinoma in situ. Recent studies exploring breast-conserving surgery with and without radiation are outlined. Although no consensus exists on the recent studies, the emergence of ductal carcinoma in situ as a cancer with both significant pathologic subtypes and significant differences in clinical presentation is clear. Concerning the role of radiation in invasive breast cancer, all reports indicate continuation of the earlier observed success. Predictors for recurrence, the diagnosis of recurrence, and the relationship of an apparent isolated local recurrence with the eventual development of distant metastatic disease are reviewed. The outcome of treatment with breast-conserving surgery in radiation in unusual situations is also presented, including patients with silicone prostheses, those presenting with an axillary mass and occult breast disease, and those with multiple primary tumors in the same breast. The clinical evidence continues to support radiation delivered after mastectomy in patients who are at high risk for locoregional recurrence. Systemic adjuvant chemotherapy alone does not appear to prevent many of these recurrences. With the improved local control following treatment with both adjuvant systemic therapy and comprehensive postoperative radiation, preliminary reports are also documenting advantages in terms of disease-free survival.