The imidazole ring is ubiquitous in nature and imidazole functionality plays a critical role in many structures within the human body, notably as histamine and histadine. Imidazoles offer many biophysical interactions including their ability to hydrogen bond with drugs and proteins. In contrast, imidazolium salts have lost their strong hydrogen-bonding ability through alkylation of both nitrogens, but they are able to aggregate electrostatically. Imidazolium salts are used to extract metal ions from aqueous solutions, dissolve carbohydrates, create polyelectrolyte brushes on surfaces, coat metal nanoparticles, provide antimicrobial action, and create oriented liquid crystals. Bioactive applications include imidazolium hydrogels, antiarrhythmics, and anti-metastic agents. This review will describe the synthesis and design of imidazole derivatives and imidazolium-containing polymers as bioactive materials. Imidazole-based polymers readily associate with biological molecules through hydrogen-bonding, and imidazolium analogs offer electrostatic interactions, aggregation, and self-assembly. Design of novel imidazole- and imidazolium-based macromolecules remains as an exciting and emerging field. (C) 2010 Elsevier Ltd. All rights reserved.