Lots of studies have demonstrated the utility of indocyanine green(ICG) angiography, especially with the assistance of SPY system, can predict the flap condition, both donor and recipient sites. In breast reconstruction after mastectomy, especially with DIEP flap or pedicled TRAM flap, we have to assess such a flap with large volume but various vascular conditions as well as to assess the skin condition after mastectomy. In the past time, to realize the vascularity of flap and experiences is important. However, with the assistance of ICG, we can choose the best part of flap and also, to sacrifice regions with poor vascularity easier. Not only flap monitor but also lymph node detection, in some conditions, ICG can be used to assess sentinel lymph nodes(SLNs), such as melanoma of toes to inguinal regions and breast cancers to axilla. Intradermal injection by ICG was done at the periareolar regions and the breast quadrants in which the tumor resided, following breast massage for around 10 min. The ICG can used to detect SLN with better effectiveness than methyl blue, even if slightly lower than technetium 99m. Therefore, applications of ICG have dual benefits in patients with breast cancer  surgery and reconstruction.