Ductal carcinoma in situ is a premalignant disease of the breast with a rapidly rising incidence. For women with localized ductal carcinoma in situ, randomized trials have shown that radiation therapy following conservative surgery lowers the relative risk of progression to invasive disease by 60%. Therefore, following conservative surgery, radiation therapy to the breast is generally considered a reasonable standard of care. However, several clinical trials have investigated the safety of conservative surgery alone without radiation for select women with small tumors of low histologic grade excised with widely negative margins. At present, results of these trials are conflicting, and, therefore, radiation therapy is generally recommended following conservative surgery, even for patients with favorable pathologic characteristics.