In recent years, a marked increase in the incidence of neurosyphilis (NS) has been observed in the Russian Federation. In 2017, 86% of all newly diagnosed cases of NS were late forms of specific damage to the nervous system, which until recently were considered a casuistic rarity. The most common form of late NS, according to modern research, is paralytic dementia, characterized by a wide variety of psychiatric, neurological and cerebral symptoms. The clinical manifestations of paralytic dementia are non-pathognomonic, and therefore the correct diagnosis can be made only based on the results of serological reactions to syphilis and a comprehensive study of cerebrospinal fluid. Patients with paralytic dementia, usually, initially visit psychiatrists and neurologists, who very often lack proper caution regarding late NS, which contributes to untimely diagnosis of the disease and severe irreversible consequences for the health of patients. Management of patients with paralytic dementia is an interdisciplinary problem requiring coordination and continuity of actions of doctors of various specialties. This article describes two cases of paralytic dementia in middle-aged HIV-negative men, who did not receive specific therapy in the past for syphilis. A review of the literature on this problem is given.