Site-specific control of drug delivery to the tumor has been grately expected to achieve successful cancer chemotherapy by using carrier systems targeted to the tumor by controlling their in vivo physical and/or chemical interactions. For anticancer targeting systems, several types of drug carriers have been investigated. However, non-selective scavenging by the reticuloendothelial system is a serious problem even when carriers are monoclonal antibodies. Recently, the anticancer targeting systems are approched with the overall perspective of in vivo interactions of the targeted carrier with biocomponents including proteins, cells and organs as well as the binding affinities of the targeted carrier with cancer cells. The authors, herein, classify and explain the today's carrier systems for cancer chemotherapy into three categories : 1) Active targeting utilizing specific molecular recognition of antibodys or receptors, 2) Passive targeting achieved by controlling biodistribution of the carriers by regulating their pyhsical properties such as a size, hydrophilicity, charge, etc., and 3) Drug modulation using intelligent materials controlling drug biodistribution and/or drug bioactivity in response to external, physical stimuli such as temperature, light, magnetism, etc.. These systems are further developed by a conjunction of the systems resulting in amplification of the targeting efficacy. In order to achieve clinical application of these targeted carrier systems, interdisciplinary research of pharmaceutics, engineering and medicine must be required. Advanced science has been developing for design of the novel drug targeting system. In the future, progressive improvement of this area is expected to achieve effective cancer chemotherapy.