Large scale population monitoring by cytogenetics would require vast amounts of effort for meaningful results. Computer techniques promise to assume some of this burden and thus render large scale monitoring a more practical alternative than it is now. A system recently developed at the California Institute of Technology, Jet Propulsion Laboratory and the City of Hope Medical Center, contains many of the features required by a large scale population monitoring system. One part of the system is a semi-automated slide preparation assembly which can process up to 576 specimens per day with uniform treatment. The second part of the system consists of a computer-controlled microscope which performs automatic slide search, metaphase location, and karyotype analysis under the interactive supervision of an operator. While the system was developed primarily for clinical cytogenetics, some aspects of our operating experience suggest promising approaches for population cytogenetics.