Immunoprecipitation (IP) is one of the most widely used and selective techniques for protein purification. Here, a miniaturised, polymer-supported immunoprecipitation (mIP) method for the onchip purification of proteins from complex mixtures is described. A 4 ml PDMS column functionalised with covalently bound antibodies was created and all critical aspects of the mIP protocol (antibody immobilisation, blocking of potential non-specific adsorption sites, sample incubation and washing conditions) were assessed and optimised. The optimised mIP method was used to obtain purified fractions of affinity-tagged protein from a bacterial lysate.