The antimicrobial effect of ionic liquids (ILs) as comonomers in polyurethane surface coatings was investigated. Ionic liquid-containing coatings were prepared from a hydroxyl end-capped liquid oligoester and a triisocyanate crosslinker. Three different commercially available hydroxyl end-capped ionic liquids were covalently incorporated into the coatings in order to end up with antimicrobial polyurethane films. The ionic liquids used in this study were chosen because of their structural similarities to other antimicrobial quaternary ammonium compounds (QACs). Prepared films have been examined against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli type bacteria, and showed strong antimicrobial activity.