This paper is concerned with auto- matic segmentation of high resolution digitized metaphases. This includes auto- matic detection and rejection of inter- phase nuclei, stain debris, and other “noise”; automatic detection and seg- mentation of touching and overlapping chromosome clusters; and automatic re- jection of cells which are evaluated as be- ing incomplete, or incorrectly segmented, or where the cell is otherwise unsuitable for further analysis. In this paper, a rule-based approach is described which treats the cell as a whole rather than as a series of individual chro- mosomes or clusters. The rules adapt classification and segmentation parame- ters for each cell. Initially, different sets of parameters are chosen according to the staining method of the cells, and the