the invention disclosed relates to intrinsically bacteriostatic synthetic polymer membranes , and to process for the manufacture thereof . in one embodiment , bacteriostatic metal ions are attached to a surface of a preformed synthetic polymer membrane by static adsorption / adsorption and reduced to the metal in situ . in another embodiment , the instrinsically bacteriostatic membranes are formed by providing a casting solution of a membrane forming synthetic polymer and bacteriostatic metal ions , and casting into a bath containing a reducing agent for the metal ions to form the membrane containing the metal ions incorporated therein .