Syphilitic meningoencephalitis, tabes dorsalis, and progressive paralysis are not responsible for specific and characteristic cytologic findings in the CSF. However, cytologic monitoring of the CSF provides valuable information on the course of the illness and success of therapy. Pleocytosis of the CSF can exceed 3,000/mm3 in rare cases of syphilitic meningoencephalitis, but values under 500/mm3 are more usual. As in the case of other infectious disorders, granulocytosis is characteristic of the initial phase. The granulocytes are soon replaced by transformed lymphocytes, plasma cells, and monocytes, though a limited number of granulocytes can usually be found over a long period of time. The granulocytes never attain the same proportions as in tuberculous meningoencephalitis. Penicillin therapy can quickly normalize the CSF.