The fabrication of robust biomolecule microarrays by reactive microcontact printing (mu CP) on spin-coated thin films of poly(N-hydroxysuccinimidyl methacrylate) (PNHSMA) on oxidized silicon and glass is described. The approach combines the advantages of activated polymer thin films as coupling layers, characterized by high reactivity and high molecular loading, with the versatility and flexibility of soft lithography. The transfer of amino end-functionalized poly(ethylene glycol) (PEG) from oxidized poly(dimethylsiloxane) elastomer stamps to PNHSMA films is shown by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, fluorescence microscopy, and ellipsometry measurements to result in covalent coupling and identical grafting densities, as found previously for coupling from solution. The PEG-protected areas effectively inhibit the adsorption of fluoresceinamine, bovine serum albumin, as well as 25-mer DNA, while the unreacted N-hydroxysuccinimidyl methacrylate ester groups retain their reactivity towards primary amino groups. Biomolecule microarrays have been thus conveniently fabricated in a two-step procedure. The hybridization of target DNA to immobilized probe DNA in micropatterns proves the concept of reactive mu CP on activated polymer films for obtaining robust platforms for biomolecule immobilization and screening.