The dependence of the strain rate sensitivity (SRS) of alpha-Fe and Al 99.5, as typical representatives of fcc- and bcc-type metals, on the testing temperature and with respect to the microstructure is investigated. In particular, the differences between conventional grain size (CG) and ultrafine grain size (UFG) are pointed out. UFG Al 99.5 generally shows an elevated SRS compared to CG Al 99.5. In case of a-Fe the SRS of the UFG state is decreased at room temperature, but increased at 200 degrees C, compared to the CG state. It is shown that the SRS also influences the ductility of UFG-metals in tensile tests.