Reticulocyte count in peripheral blood determines the erythropoietic activity, reticulocyte counting is the basic and one of the most commonly used methods in diagnostic hematology. Reticulocytes are juvenile erythrocytes containing the remains of basophilic ribonucleoproteins. The remains present material which Brilliant cresyl blue solution binds to and in turn creating granulated or fibrous blue-black precipitate. Juvenile reticulocytes have the greatest concentration of precipitated material; lower amount of granules or short fibers may be microscopically detected while observing older reticulocytes. This method uses fresh, non-fixed juvenile erythrocytes.