Quantum dots (QDs) are semi-conductor nanocrystals that emit fluorescence on excitation with a light source. They have excellent optical properties, including high brightness and resistance to photobleaching. Their spectroscopic properties can be modulated by many factors. Recent progress in developing QDs enable us to control the size, shape and surface functionality of nanoparticles for potential application in cancer imaging. QDs with near-infrared emission could be applied to identify sentinel lymph-node. Conjugation of QDs with biomolecules could be used to target tumors in vivo. This article reviewed recent developments and issues in nanotechnology with a particular focus on applications to the surgery.