During a period of eighteen years, from 1909 to 1926, we observed the patients suffering from neurosyphilis in our psychiatry department, and in the following average annual percentage of the total number of patients treated in this department: Paralysis progressiva 0.8%, Tabes dorsalis 1.1%, other Neurosyphilis 0.8%. 1) The number of the patients seems to be increasing. 2) Most patients are infected with syphilis for the first time in their twenties, but the diseases first appear with most patients in their thirties and forties. 3) The incubation of the diseases is shorter with old than young patients who have not undergone any antisyphilitic cure. 4) Few neurosyphilitic patients seem to have had a syphilitic cutaneous eruption before. 5) The alleged recent tendency towards the shortenning of the incubation of these diseases has never been proved. But most patients have not been thoroughly treated with any antisyphilitic remedies before.