SU-8 is an epoxy-based photosensitive resist, which is currently used for a large variety of MEMS and lab-on-a-chip applications. Here, we demonstrate a one-step process to functionalize SU-8 with DNA probes. The immobilisation procedure relies on direct coupling of DNA to SU-8 and resulted in surfaces with functional capture probe densities of approximately 10 fmol/mm(2) as determined by hybridisation assays with fluorescent labelled target molecules. A comparable density of functional capture probes was measured on commercial aldehyde coated glass. DNA probes did not decrease in hybridisation performance after 10 min incubation in water at 98 degrees C prior to hybridisation, indicating a covalent bond between DNA and SU-8. Finally, DNA microarrays of high quality were obtained on SU-8 by contact printing of probe solution directly on SU-8 demonstrating a simple method for the implementation of microarrays in microsystems.