A hemocytometer plate, is a counting method that measures the number of blood cells in the peripheral blood. Generally observed under a microscope, a hemocytometer plate enables the analysis of the number of red blood cells, white blood cells, and platelets in a complicated process. A suitable blood specimen is usually available and then the blood specimen is dropped onto the plate and the exact number of blood cells counted on the plate is eventually calculated by counting and observing. This was a common method of counting blood cells in the past, and the plate was also able to count the number of microorganisms, such as counting bacteria, yeast, etc. With the development of science, the hematocrit plate counting method has now been eliminated in clinical practice. Nowadays, blood cell automatic analyzer is mainly applied to count the number of various blood cells in peripheral blood, which has the advantage of fast and accurate. Therefore, blood cell counting plates are generally still used occasionally in certain research laboratories, and have basically been eliminated in the clinical setting.