The tremendous contribution of nanotechnology to the treatment and diagnosis of medical diseases has recently attracted the attention of anticancer researchers. Most of the new nanoparticle carriers have improved drug bioavailability and reduced the cytotoxic effects of the drugs. This article presents an overview of the recent advances of nanotechnology in cancer therapy. It covers the mechanisms of cellular uptake for anticancer drugs delivered in nanoscale systems by either active or passive targeting. The various nanoscale systems employed in drug delivery and their immense potential in diagnosis and imaging of cancerous tumors are also addressed.