Reduced field-of-view (rFOV) imaging has been achieved in 2D imaging. Although 2D rFOV can reduce image distortion and produce high in-plane resolution in EPI, the through-plane resolution remains poor and signal voids persist. We report a 3D reduced field-of-view imaging (3D-rFOVI) sequence to extend the conventional 2D rFOV imaging to 3D by using a slab-selection 2D RF pulse in conjunction with through-slab phase-encoding. This sequence features high isotropic spatial resolution in EPI images while reducing off-resonance effects that cause image distortion and signal voids. We have successfully applied the 3D-rFOVI technique to fMRI and DWI.