Fever in leukemia patients is not a good thing. The cause of fever in leukemia is usually due to the presence of a large number of leukemia tumor cells in the body of a leukemia patient. A person with leukemia may also have a low immune system, which can lead to viral or bacterial infections that can cause a person with leukemia to have a fever. It can occur at any stage of the disease and may be low or high fever, but neither is good. Leukemia, also known as blood cancer, is a malignant tumor of the blood-forming system. Abnormalities in the blood-forming tissues in the bone marrow lead to a decrease in the bone marrow’s ability to produce other blood cells. Its cause is unknown and may be related to factors such as ionizing radiation, long-term exposure to chemicals, and genetic inheritance of viral infections. If a leukemia patient develops a fever, the patient is advised to seek prompt medical attention.