A medical device and a method for imparting antibacterial properties to the device, made from hydrophobic polymer, particularly to urinary latex catheters comprises treatment of the device by spreading, dipping or spraying and consequent drying with natural biodegradable polymers (A), composition including a cross-linking agent (B) for partial cross-linking the mentioned polymer and an anti-microbial agent compatible with A and B. The polymer may be from a group of polysachharides, for example polyglucosamine-chitosan. For partial cross-linking of the polymer substances having aldehyde groups such as glucose or evolving aldehydes such as hexamethylenetetramine or their mixtures are used. The polymer is able to form on the surface of the medical device a thin film that swells in wet or moisturized state once inserted into the body. In the swollen state it will gradually release an anti-microbial agent.