The advent of mammographic breast screening has increased the detection of ductal carcinoma in situ (DCIS), which now accounts for 15-20% of all breast cancer. While symptomatic DCIS has been treated satisfactorily by mastectomy, this may be an overtreatment of smaller screen-detected lesions. Although local excision, with or without radiotherapy, is associated with a significant risk of local recurrence of DCIS or invasive cancer, salvage surgery is usually successful. The long-term breast-specific mortality rate of treatment by mastectomy and local excision are similar. Whereas mastectomy is still appropriate for women with lesions > 30 mm in diameter or centrally placed and for those women who demand the best possible disease-free survival, local surgery should otherwise be considered.