Syphilis is relatively rare in Poland at present, but it still must be taken into consideration in differential diagnosis of central nervous system (CNS) disorders. Late symptomatic (tertiary) manifestations of the disease may be difficult to recognize due to their rarity and tendency to manifest after many years of asymptomatic infection, which makes the connection with epidemiologic risk factors and symptoms of the primary infection hardly traceable. We describe a case of patient with a classic presentation of a parenchymal CNS syphilis presenting as general paresis, which was diagnosed with a delay and only after extended serological diagnostics had been prompted by false positive results of screening serologic test for Lyme disease.