Radiotherapy is a critical component in the treatment of breast cancer, a disease that is estimated to have affected 203,500 US women in 2002. According to the data from some series, an estimated 90% of patients treated with radiotherapy for breast cancer will develop a degree of radiation-induced dermatitis. This review describes the indications and techniques of radiotherapy for breast cancer. The pathophysiology, clinical presentation, and contributing factors of radiation-related skin injury are discussed. A review of recent clinical research addressing skin toxicity is provided.