The greatest impact of nanotechnologies in cancer therapy is in the realm of drug delivery. The therapeutic index of nearly all drugs could be improved if they were more efficiently delivered to their biological targets through appropriate application of nanotechnological tools. An safer and effective cancer drug or drug delivery system should fulfil the following requirements: a) it must have an adequate drug concentration which allows an effective dose at the tumor cells, b) should be targeted to cancer cells, and prevent uptake by normal cells, c) should have a long half-life in blood circulation, d) should have good bio compatibility, and stability which retain the drug until it reach to target. Nanotechnology has the potential to have a revolutionary impact on cancer diagnosis, prevention and therapy.The use of nanotechnology in cancer treatment offers the possibility of destroying cancer cells with minimal damage to healthy tissue and organs. Efficacy and specificity are two basic requirements for cancer therapy. With the advancement of nanotechnology, the application of nano-materials as drug carriers can improve anticancer treatments.