The purpose of this study was to evaluate the effects of the application of chitosan coating containing natamycin on the physicochemical and microbial properties of semi-hard cheese. Three cheese groups were prepared: samples without coating, samples coated with chitosan and with chitosan containing 0.50 mg mL(-1) of natamycin, whose minimum inhibitory concentration was previously determinated on cheese surface. Microbiological analyses showed that natamycin coated samples presented a decrease on moulds/yeasts of 1.1 log (CFU g(-1)) compared to control after 27 days of storage. Addition of natamycin also affected O(2) and CO(2) permeability, increasing from 7.12 to 7.68 x 10(-15) g.(Pa s m)(-1), and from 10.69 to 64.58 x 10(-14) g.(Pa s m)(-1), respectively. The diffusion coefficient values of natamycin from the film to phosphate buffered saline solution and to the cheese were 3.60 x 10(-10) and 1.29 x 10(-12) cm(2) s(-1), respectively. This study demonstrated that chitosan-based coating/films can be used as release system containing natamycin to create an additional hurdle for moulds/yeasts in cheese thus contributing to extend its shelf-life. (c) 2010 Elsevier Ltd. All rights reserved.