This invention relates to an antimicrobial master batch polymer composition comprising: (a) a thermoplastic alkyl polymer, and (b) an antimicrobial as well as to a polymer composition comprising the antimicrobial master batch polymer composition and a thermoplastic alkyl polymer. This invention also relates to a fabric or moulded product comprising the polymer composition. In addition, the invention relates to a method of making the antimicrobial master batch polymer composition, comprising the steps of: (a) mixing the thermoplastic alkyl polymer powder with the antimicrobial powder, (b) melting the mixture, and (c) cooling the mixture.