Non-invasive in vivo imaging offers great potential to facilitate translational drug development research at the animal testing phase. The emerging luminescent nanoparticles or quantum dots provide a new type of biological agents that can improve these applications. The advantages of luminescent nanoparticles for biological applications include their high quantum yield, color availability, good photo-stability, large surface-to-volume ratio, surface functionality, and small size. These properties could improve the sensitivity of biological detection and imaging by at least 10- to 100-fold and make them an exceptional tool for live-cell imaging. In this review patents on applications of semiconductor quantum dots for in vivo imaging are discussed.