A study of creep mechanisms of ferritic ODS alloys was based on high temperature tensile/compression tests combined with electron microscopy analysis of deformed specimens and in situ observations of dislocation motion under stress. The flow stress, its strain-rate sensitivity and its temperature dependence were discussed in terms of solid solution hardening, mutual dislocation interaction, the Orowan process, a thermally activated detachment model and solute drag effects. The mechanisms controlling the flow stress of ferritic ODS alloys were identified.