We are reviewing 40 patients with noninvasive intraductal carcients; 10% developed oppostie breast cancer of the invasive variety. Twenty-one patients underwent radical mastectomy in which one patient was found to have a positive axillary node. The 19 remaining patients had total mastectomy alone. No recurrence of death attributed to intraductal carcinoma was found in 39 patients available for follow-up.