We measured central corneal endothelial cell density and area from contact specular photomicrographs of ten normal and ten abnormal corneas, comparing the precision, cost, and speed of four methods: a rectangle, planimeter, digitizer, and cell sizer. The rectangle, planimeter, and digitizer gave results that differed less than 10% from each other; therefore, the three methods can be used interchangeably for clinical purposes. There are statistically significant differences among the three techniques that may be important in basic research. The cell sizer gave a rapid, less precise estimate of mean cell area and cell density. The planimeter and digitizer measured individual endothelial cell size, and the latter entered data directly into a computer that printed both a copy of the endothelial mosaic and a histogram of cell size frequency, and computed cell density and mean cell area. We make the following recommendations: Count cells in a rectangle used for routine clinical measurement. use a cell sizer for rough estimation, as in an eyebank setting. Use a computerized digitizer to study individual endothelial cell size.