Ferromagnetic resonance measurements were performed on CoO/Co exchange biased microstructures with a low-temperature magnetic resonance force microscope (MRFM). The MRFM instrument relies on piezoresistive force detection, and the magnetic tip attached to the cantilever acts as a field gradient source. These features extend the applicability of the MRFM that can also be used as a conventional magnetic force microscope. Spatial variations of the MRFM signal, which are induced by a spatially modulated exchange bias, are monitored with a lateral resolution of about 5 mum. (C) 2004 American Institute of Physics.