Ductal carcinoma in situ (DCIS) represents a breast lesion that is diagnosed with increasing frequency, mainly due to the wide use of screening mammography. Today, DCIS comprises 15-25% of all breast cancers detected at population screening programs. Consequently, the concepts of properly managing such patients assume a greater importance in everyday practice. Mammographically detected microcalcifications are the most common presentation of DCIS. Despite recent technological advances (including Stereotactic-guided directional vacuum-assisted biopsy), mammographically guided wire biopsy remains the "gold-standard" for obtaining a histological diagnosis in patients with non-palpable, mammographically detected DCIS. Management options include mastectomy, local excision combined with radiation therapy, and local excision alone. Given that DCIS is a heterogeneous group of lesions rather than a single entity, and because patients have a wide variety of personal needs that must be addressed during treatment selection, it is obvious that no single approach will be appropriate for all forms of DCIS or for all patients. Careful patient selection is of key importance in order to achieve the best results in the management of the individual patient with DCIS. Axillary lymph node dissection is unnecessary in the treatment of pure DCIS, but it is indicated when microinvasion is present. In these cases, sentinel lymph node biopsy may be an excellent alternative. In the NSABP B-24 trial, tamoxifen reduced both the invasive and non-invasive breast cancer events in either breast by 37%. Nearly all patients who develop a non-invasive recurrence following breast-sparing surgery are cured with mastectomy, and approximately 75% of those with an invasive recurrence are salvaged. Selected patients initially treated by lumpectomy alone may also undergo breast-conservation therapy at the time of relapse according to the same strict guidelines of tumor margin clearance required for the primary lesion; radiation therapy should be given following local excision. The use of systemic therapy in patients with invasive recurrence should be based on standard criteria for invasive breast cancer.