Semiconductor quantum dots based on II - VI materials may be prepared to develop good biolabeling properties. In this study we present some well-succeeded results related to the preparation, functionalization and bioconjugation of CdY (Y=S, Se and Te) to biological systems ( live cells and fixed tissues). These nanostructured materials were prepared using colloidal synthesis in aqueous media resulting nanoparticles with very good optical properties and an excellent resistance to photodegradation. (C) 2008 Elsevier B. V. All rights reserved.