14 cases of tabes dorsalis, 4 cases of dementia paralytica, 3 cases of lues cerebri, and 1 case of syphilitic meningomyelitis are reported as observed over a 10-year period (1967-1976). Tabes has the peculiarity of revealing itself with pictures characterized by scarcity and mildness of objective neurological manifestations. Dementia paralytica, cerebral meningo-vascular syphilis and spinal syphilitic meningomyelitis remain constant in that they still present typical pictures, i.e., those which are classically described in early literature. In our neurosyphilitics, the most vulnerable average age for the late luetic manifestations in the nervous system in 50 years. In most of the patients examined, changes of the histochemical composition of cerebrospinal fluid are present. The colloidal benzoin test that, in almost all the cases, reveals itself by pathological precipitations is extremely important for a correct diagnosis. In more than one third of the 22 neurosyphilitics examined, all the non-treponemal serological reactions are negative both in the blood and in the cerebrospinal fluid. On the contrary, we assign a greater diagnostic importance to TPI and FTA test, which give positive results in the blood in 65 and 70% of the cases, respectively.