There are a number of advantages in using a mechanised microscope for scoring a large number of metaphase cells from human blood lymphocyte preparations. Following the development of an automatic metaphase spread finding machine based upon a large motorized microscope and a synchronous closed circuit television camera and flashing light source, a much smaller machine which is more appropriate to the cytogenetics laboratory, but with a similar metaphase finding performance was constructed. The new machine which consists of a Cambridge Instruments 1 .mu.m stepping microscope stage, a linear diode array scanner and a computer is described in detail. Metaphase finding performance figures for various orcein stained human blood lymphocyte preparations are given.