Recording electron microscope images of frozen-hydrated samples under cryo-conditions is a difficult and challenging task. The inherently low sample contrast makes accurate focusing difficult. Furthermore most frozen-hydrated samples are very beam sensitive so that electron dose on the sample must be kept to the minimum. In recent years, the new generation of cooled slow-scan CCD (SSC) cameras have shown superior properties in sensitivity, resolution, dynamic range, linearity, and more importantly their ability to display images on-line. Computer control of electron microscopes via the standard RS232C serial interface has been greatly facilitated by the use of on-line CCD images. We have developed a software package that allows cryo-electron microscope images to be automatically acquired onto a CCD camera via computer control of the microscope. This fully automated feature allows quality cryo-electron microscope images to be recorded with increased efficiency and enhances the possibility of obtaining three-dimensional reconstructions from images.