Reticulocytes are immature red blood cells. A reticulocyte count is a test used to measure the level of reticulocytes in the blood. Reticulocytes are formed in the bone-marrow and are released into the bloodstream. If your red blood cell count is too low or too high your body will try to achieve a balance by producing and releasing more or less reticulocyte. Reticulocyte count can help in diagnosis of various conditions like anaemia and bone marrow failure. It is also used to track the progress after chemotherapy, radiation therapy, bone marrow transplant or treatment of anaemia.