The development of new fluorophores has experienced a tremendous advance over the last two decades. The unique photophysical properties of quantum dots (QDs), such as their large Stokes shifts and exceptional brightness, make them attractive probes in flow cytometry applications. In this chapter, the spectral overlap and the fluorescence intensity of a single Qdot nanocrystal species (Qdot-655) was investigated in the context of a panel containing conventional fluorophores. Certain compensation issues remain because of the unique absorption characteristics of QDs. To demonstrate the potential of QDs for multicolor flow cytometry, human lymphocytes were surface stained with an eight-color panel where one of its standard violet laser reagents, CD4 AmCyan, was substituted with the CD4 Qdot-655 conjugate.