Ductal carcinoma in situ (DCIS) of the breast historically has been a disease detected by physical examination, diagnosed by open surgical biopsy, and treated by mastectomy and axillary dissection. It is now increasingly detected by screening mammography, diagnosed by needle core biopsy, and treated by lumpectomy, with axillary dissection having been abandoned and sentinel node biopsy being used in axillary staging. However, outcomes related to sentinel node biopsy in DCIS have not been validated in well-controlled clinical trials. Current guideline recommendations are to use sentinel node biopsy when needle core biopsy is highly suspicious for invasive cancer or where there is a high-risk DCIS when lumpectomy identifies invasive breast cancer with the DCIS, or when mastectomy is performed for extensive DCIS. Routine use of sentinel node biopsy for DCIS is not supported.