High lymphocytes do not necessarily mean leukemia. The diagnosis of leukemia does not depend on routine blood tests, although abnormal blood tests can be helpful in indicating the presence of leukemia. If the lymphocytes are high, there may be an elevated or decreased white blood cell count at the same time. To rule out leukemia, a peripheral blood smear is performed. If a large number of primitive or naive lymphocytes are seen in the peripheral blood smear and the percentage of mature lymphocytes is significantly higher, further bone marrow aspiration is required to see if there are a large number of primitive or naive lymphocytes in the bone marrow to further confirm the diagnosis of leukemia.