A 58-year-old man was admitted with a progressive, subacute asymmetrical paraparesis. The patient denied a previous syphilitic infection, but spinal fluid examination disclosed a lymphocytic pleocytosis, hypoglycorrhachia, and a positive serologic test for syphills. Clinical improvement resulted from a 14-day course of penicillin. Syphilitic involvement of the nervous system appears to be increasing in the United States and should be included in the differential diagnosis of progressive paraparesis.