Antimicrobial packaging could enhance food storage life and safety. An antimicrobial moiety that is permanently bound to the polymer surface and does not leach has particular appeal. The use of 193 nm UV irradiation to convert amide groups on the surface of nylon to amines having antimicrobial activity has been reported previously. We prepared materials accordingly and explored their mode of action and activity against pathogens. Three food related bacterial strains, Staphylococcus aureus, Pseudomonas fluorescens and Enterococcus faecalis were exposed to antimicrobial film in 0.2 M sodium phosphate buffer (pH 7.0). Samples were held shaken at 100 r.p.m. in a 25°C incubator. The antimicrobial film was effective in reduction of microbial concentration in the bulk fluid for all food-related bacteria tested. The effectiveness was dependent on the bacterial strain. Adsorption of bacterial cells diminished the effectiveness of amine groups. Experimental results indicate that the decrease in concentration of bacterial cells in bulk fluid is more likely to be the bactericidal action than adsorption of live cells. © 1998 John Wiley & Sons, Ltd.