Effective antimicrobial polymers have been attracting more interests because of the low propensity to cause drug-resistant microorganisms. The recent progresses in antimicrobial polymers are updated according to the action approaches, that is, antimicrobial polymers with free mobility or fixed on surfaces, respectively. Free antimicrobial polymers kill pathogens majorly via electrostatic interaction followed by disruption of the cell membranes; strong antimicrobial activity of primary/secondary amines, new chemical units, and peptides without facial amphiphilicity are highlighted; and the dependences on amphiphilicity, topology, and self-assembly profiles are summarized. Antimicrobial polymers fixed on surfaces kill pathogens via interaction with the cell membranes of pathogens via electrostatic or hydrophobic interaction; approaches to antimicrobial surfaces based on covalently grafting, anchoring, and bulk-mixing of polymers are summarized; and new designs of sustainable antimicrobial surfaces and hydrogels are highlighted. Deep biology understanding and development strategies of materials are suggested for the future. (C) 2016 Wiley Periodicals Inc.