Nanotechnology refers to the interactions of cellular and molecular components and engineered materials—typically, clusters of atoms, molecules, and molecular fragments into incredibly small particles—between 1 and 100 nm. Nanometer-sized particles have novel optical, electronic, and structural properties that are not available either in individual molecules or bulk solids. The concept of nanoscale devices has led to the development of biodegradable self-assembled nanoparticles, which are being engineered for the targeted delivery of anticancer drugs and imaging contrast agents. Nanoconstructs such as these should serve as customizable, targeted drug delivery vehicles capable of ferrying large doses of chemotherapeutic agents or therapeutic genes into malignant cells while sparing healthy cells. Such “smart” multifunctional nanodevices hold out the possibility of radically changing the practice of oncology, allowing easy detection and then followed by effective targeted therapeutics at the earliest stages of the disease. In this article, we briefly discuss the use of bioconjugated nanoparticles for the delivery and targeting of anticancer drugs. Mol Cancer Ther 2006;5(8):1909–17