We report on the first sub-arcsecond resolution mid-IR images of the nuclei of galaxies from the IRAS ultraluminous sample. This sample contains galaxies which emit most of their energy in the far-infrared (10-100μm) and have luminosities approaching that of quasars. Previous observations in the mid-IR using single element detectors suggest that the IR luminosity is derived from a region smaller than the instrumental aperture, typically 5″(1.6 kpc at 65 Mpc). Our observations are capable of imaging the morphology of the mid-IR emission region to a factor of eight smaller than previously known.