Introduction: Methylene blue dye has been used worldwide successfully with few complications in breast surgery. We present two different complications involving methylene blue: 1) skin and parenchymal necrosis when dye was injected in a subdermal fashion and 2) Mycoplasma infection caused by contaminated methylene blue in breast reduction surgery. Methods: We present two cases seen at the University of Arizona during 2008 and referred to a breast surgeon for management. We evaluated and managed complications of methylene blue dye injected by 2 referring surgeons for different indications. A review of the literature was performed. Results: The first case is a 67 year old female diagnosed with infiltrating ductal carcinoma o f the left breast for which she was treated by her initial surgeon with left segmental mastectomy and sentinel node biopsy. The operating surgeon injected methylene blue in a subareolar subdermal fashion (distant from the primary tumor); unfortunately the patient suffered skin and breast necrosis requiring multiple surgical debridements and finally achieving delayed primary closure. The second case is a 45 year old female with infiltrating lobular carcinoma with a history of Mycoplasma infection secondary to methylene blue injected for breast reduction surgery. She required multiple debridements and had granulomas masquerading as cancer on MRI that confounded her extent of disease. Conclusions: The use of methylene blue dye in breast surgery is not without risk. In both cases methylene blue was responsible for complications requiring surgical debridement for local wound problems. In each case severe necrosis and infection were present. Methylene blue may cause not only significant morbidity, but may also produce cosmetically unsatisfactory results.