If the lymphocyte percentage is high, it is fine if it is physiologically high, but if it is pathologically high, it needs attention. 1. Physiological high, generally 4~6 days after birth, the newborn’s lymphocyte percentage will rise to 50%, which belongs to the physiological high, with the growth of age, it will gradually return to normal, don’t need to worry about it, and don’t need to take special treatment. 2. Common causes of pathologically high lymphocyte percentage include viral infections, lymphoblastic leukemia and aplastic anemia. (1) Common viral infections, such as viral colds, measles, rubella, etc., can cause an increase in the percentage of lymphocytes, which should be noted. It is important to pay attention to whether there is fever, and take appropriate measures in time, such as ibuprofen oral antipyretic and so on. (2) Lymphoblastic leukemia, such as acute lymphoblastic leukemia, in which a large number of immature lymphocytes are released into the peripheral blood, leading to an increase in the percentage of lymphocytes. Chronic lymphocytic leukemia has a significant increase in more mature lymphocytes in the peripheral blood, resulting in an elevated lymphocyte percentage. This should be taken seriously and a peripheral blood smear or bone marrow smear can be performed. (3) Aplastic anemia, due to decreased hematopoiesis in the bone marrow, is characterized by a reduction in the erythrocyte, platelet, and granulocyte lineages, and a relative increase in the lymphocyte percentage due to a decrease in the granulocyte percentage. This should also be taken seriously. There may be other reasons for high lymphocyte percentage, it is recommended to go to the hospital in time to find out the cause of the disease, under the guidance of the doctor to treat the cause of the disease.