Leukopenia is very common in hematology clinics and is often detected by physical examinations in the unit or by blood tests for other diseases, most of which have no conscious symptoms. Most patients have no change in laboratory tests over the years, some have evidence of autoimmune disease (e.g., Hashimoto’s thyroiditis, dry syndrome, or even systemic lupus erythematosus), some have evidence of chronic viral infections (e.g., hepatitis B or C virus infection), some have mild splenomegaly from a young age for which no cause can be found, and some have a family history of leukopenia without any abnormality other than leukopenia. Most cases of leukopenia are benign processes, with leukocytes of about 3×109/L requiring no special treatment, and the tests performed are basically those related to the above-mentioned causes. In some cases, the diagnosis is confirmed by the presence of other manifestations of some of these diseases over time, but there are still many patients with leukopenia for whom no cause can be found. For such patients, long-term follow-up is the only option. For example, some patients with myelodysplastic syndrome or even leukemia only show leukopenia in the early stage, but once they have a bone aspiration, they can find obvious pathological hematopoiesis and primitive cell increase, and are diagnosed with myelodysplastic syndrome or even leukemia. Therefore, if there is a family history of hematologic tumors, frequent exposure to radiation or chemical toxins, and patients who have received radiotherapy or isotope therapy for their disease, a bone marrow aspiration should be performed once leukopenia occurs to exclude myelopathy. Sometimes tumorigenic hyperplasia of chronic lymphoid tissue (e.g., large granulocytic leukemia) can also manifest as leukopenia, and monoclonal proliferating T lymphocytes or NK cells can be seen in the peripheral blood and are worth noting. However, do not worry too much, because in most cases, leukopenia is not a big problem and only needs to be observed. Wensheng Wang, Department of Hematology, Peking University First Hospital