Sixty-two patients with symptomatic neurosyphilis were treated with 20 or 24 megaunits of intravenous penicillin G daily for 15 to 30 days. The mean follow-up time after the treatment was 30 months. Forty-one patients had pleocytosis in the CSF before treatment. Six months and twelve or more months later, abnormal cell count was observed in 4 (9.8%) and in 3 patients (7.3%), respectively. The CSF protein level and the titers of Wassermann reaction in the CSF decreased slowly after treatment. The gammaglobulin concentration of the CSF and the immunoglobulin production inside the blood-brain barrier were still increased beyond the first year after treatment. The results of the treatment of these patients with high doses of intravenous penicillin G were not different from the results verified with lesser doses of intramuscular penicillin that were reported in the literature.