There are a few cases of leukemia without fever, mostly in the early stages of leukemia when there is no co-infection and the leukemia cells have not yet proliferated. Fever caused by leukemia is mostly due to the proliferation of leukemia cells, secondary infection, and neutrophil deficiency. 1. Massive proliferation of leukemia cells: due to the massive proliferation of leukemia cells in the body, the body’s metabolism is more vigorous, and it is easy to have a low-grade fever. 2. Secondary infections: due to the leukemia, the number of leukocytes with normal immune function in the body decreases sharply, and the body’s immune ability is low, so it is easy to be combined with all kinds of infections, with stomatitis, gingivitis, pharyngitis being the most common. 3. Neutrophil deficiency: during chemotherapy, chemotherapeutic drugs can further inhibit the normal hematopoietic function of bone marrow and aggravate neutrophil deficiency, which can easily cause secondary infections and lead to high fever, which is called granulocyte deficiency with fever. Although most leukemia patients will have fever, but in the early stage of leukemia, the above factors have not yet appeared to play a role or the role is not great, there may be no fever.