BACKGROUND: Methylene blue dye (MBD) is being used as an alternative to isosulfan blue dye in sentinel lymph node (SLN) biopsies for breast cancer patients. Complications using MBD for SLN localization have not previously been reported. METHODS: A retrospective study was conducted of 24 consecutive patients who received MBD. Patients were given 3 to 5 cc of 1% MBD as peritumoral injections within the breast parenchyma and intradermally. Patients who developed local skin lesions at the injection site were queried regarding lesion appearance and when subsequent adjuvant therapy was initiated. RESULTS: Five of the 24 patients (21%) developed skin lesions at the injection site. Intradermal injections were discontinued, and only deep parenchymal injections were performed. All 5 patients had improvement of their skin lesions with silver sulfadiazine cream and no patient required debridement. Each patient received adjuvant therapy after surgery without delay. CONCLUSIONS: Our institution has experienced patients who developed skin lesions at the MBD injection site when using combined deep parenchymal and intradermal injections. With the increased use of MBD, caution should be used to avoid intradermal injections with SLN localization.