This review addresses the potential development of polymer hydrogels in terms of fast stimuli responsiveness and superior mechanical properties. The slow response and mechanical weakness of stimuli-sensitive hydrogels have been considered as the main barriers for their further development and practical application. It has been a dream of scientists to have fast stimuli-responsive hydrogels with superior mechanical performance. In this review, the principal reasons behind the poor stimulus sensitivity and mechanical strength of polymer gels are highlighted, and we present some pioneering physical and chemical efforts aimed at fabricating hydrogels with high stimuli sensitivities and/or superior mechanical properties. Polymer Journal (2010) 42, 839-851; doi: 10.1038/pj.2010.87; published online 29 September 2010