Recently, a growing number of nano-scale drug carrier systems (e.g., drug-polymer conjugates, liposomes, and polymeric micelles) attract great attention for targeting cancer therapy due to a passively selective accumulation at solid tumor tissues and a subsequent anti-cancer activity. However, for the present drug targeting carrier systems, the target-selective delivery and release of loaded drugs are incapable to control completely. To overcome these current issues, stimuli-responsive drug carriers have been developed as the next-generation drug targeting systems. If drugs can be delivered to target sites via passive targeting of stimuli-responsive carriers and then released from the carriers by external physical signals, the systems are termed "multi-targeting systems" which are quite attractive for achieving the target site selective pharmaceutical action with reducing adverse effects. As possible external signals, temperature change is one of useful stimuli due to its low invasiveness to living body system and simple site-selective application using medical devices. To install temperature-responsive function to drug carriers, temperature-responsive polymers play significant roles in signal-triggering drug release and carrier-interaction with target cells and tissues. This review introduces several molecular designs for temperature-responsive drug carriers and discusses their potentials as a smart drug targeting system for an effective cancer chemotherapy. (C) 2010 Elsevier Ltd. All rights reserved.