Sinusitis in children can lead to high white blood cells if it is caused by bacterial or viral infection; however, there is no elevation of white blood cells if it is caused by structural abnormalities of the nasal cavity, tumors, or metamorphic reactions. Sinusitis is a disease with complex etiology, but infection is the first factor causing nasal and sinusitis, mainly caused by viruses and bacteria. When the body is attacked by a virus it causes an increase in lymphocytes, which leads to an increase in the total number of white blood cells; when there is a bacterial infection in the body, it causes an increase in neutrophils, which leads to an increase in the total number of white blood cells. However, when sinusitis is caused by deviated nasal septum, enlarged nasal turbinates, hypertrophied mucosa, tumors and foreign bodies in the nasal cavity, as well as allergic reactions of the nose, there is no increase in leukocytes in the blood picture. Therefore, children with acute sinusitis may cause high leukocytes.