Macroglobulinemia is usually feverless in the absence of co-infections, and can occur in the presence of secondary infections (e.g., bacterial infections, etc.). Macroglobulinemia is a blood disorder characterized by the presence of abnormally increased amounts of IgM protein in the blood and is a malignant proliferative disorder originating in B lymphocytes. Its clinical manifestations include malaise, anemia, weight loss, headache, and bleeding. Macroglobulinemia usually does not show fever in the absence of co-infections, and fever may appear in secondary infections, such as lung infections caused by bacteria. If a patient with macroglobulinemia develops fever, the cause of the disease should be actively identified and treated accordingly. Macroglobulinemia is a malignant blood disease that requires timely treatment to avoid delays.