Quantum dot is a spatial semiconductor of periodic groups of II-VI, III-V, or IV-VI materials, which generates optically stable fluorophores upon excitations at various wavelengths (from UV-IR). To date, quantum dot technologies are used in various fields and the use in molecular biology has increased dramatically over the past years. In this review article, we would discuss the potential uses of this versatile nano crystal. Quantum dot technology is also used in cell labelling, bio-sensing, in-vivo imaging, bimodal magnetic-luminescent imaging, and diagnostics. We would also discuss toxicity issues surrounding this nano crystal and speculate about the future uses of quantum dot in large areas of biomedical sciences. © 2011 Inderscience Enterprises Ltd.