A Hitachi HU-11B electron microscope has been modified for ultrahigh vacuum operation. Differential sputter ion pumps are used to evacuate the entire microscope column, which was extensively modified to be compatible with the high vacuum, low contamination environment. Excellent beam stability and resolution have been observed with column pressures as low as 5×10−8 Torr, but the image intensifier has proved unsatisfactory for high resolution readout.