The Genetiscanner automatic metaphase finder (AMF) instrument manufactured by Perceptive Scientific Instruments, Inc. is capable of searching a microscope slide and generating a list of the stage coordinates of the metaphases within the 20 mm x 40 mm search area in ten minutes. It can process a cassette load of sixty slides in approximately ten hours, ranking the metaphases according to six categories of quality. It uses a robot arm to load and unload slides from a 60-slide cassette onto an automated microscope stage. It searches at approximately 1.5 sq. mm per second and uses automatic focus to keep the image sharp during the search. On good quality blood slides it detects greater than 80% of the metaphases with greater than 80% ranking accuracy and less than 20% false positives. It can also search amniotic fluid, bone marrow and mammalian cell culture metaphase preparations. The pattern recognition algorithms use classifiers specifically trained for each specimen type, and for the rejection of non-metaphase material. Such units have been in continuous operation for up to two years with good performance and reliability.