Thirty-two consecutive cases of ductal carcinoma in situ of the breast in women under fifty are presented. Diagnostic procedure, pathological aspects, treatment and outcome are reported. All the patients had their cancer diagnosed by mammography. The tumor was marked by stereotactic or ultrasound guided localization. Lumpectomy without axillary node dissection was the surgical treatment of thirty lesions with good cosmetic results; radiation therapy was advised in all of these cases. In two cases mastectomy with immediate reconstruction was performed because of the multifocality of the cancer, none of the patients experienced local or distant recurrence. This experience emphasizes the importance of mammographic screening for women 40 years of age, in fact this approach allowed the diagnosis of a large number of DCIS. A correct definition of the problem and a multidisciplinary therapeutical approach is warranted to prevent the high local recurrence rate reported in the past.