We developed an analysis system for the evaluation of corneal endothelial photographs. Morphological parameters including hexagonality were analyzed semiautomatically with this system. The image analyzer used consists of an image processor MC68000 and image memories 512 x 512 x 17bytes in size. The algorithm that measures the number of apices of each cell is as follows. First, all crossing points of cell borders are detected. Then, each cell is enlarged in order by three pixels in eight directions. The number of crossing points which are overlapped with an enlarged cell is detected as the number of apices of the cell. The analysis time was 7.44 +/- 1.48 min. (mean +/- standard deviation) for 40 endothelial photographs which needed no manual trace for contrast enhancement.