Sentinel lymph node (SLN) mapping is an important cancer surgery during which the first lymph node draining the site of a tumor is identified, resected, and analyzed for the presence or absence of malignant cells. Fluorescent semiconductor nanocrystals (quantum dots [QDs]) of the appropriate size, charge, and emission wavelength permit this surgery to be performed rapidly, with high sensitivity and under complete image guidance. We describe the materials and methods necessary for the production and characterization of type-II near-infrared fluorescent QDs, which have been optimized for SLN mapping. They contain a CdTe core, CdSe shell, and a highly anionic, oligomeric phosphine organic coating. We also describe how to utilize such QDs in animal model systems of SLN mapping.