Evolution of syphilis has been studied in HIV-seropositive patients with regard to progression mode and clinical pictures. Reciprocal interactions between syphilis and HIV have been suggested based on the observation of unusually aggressive forms of treponemic infection, particularly at the CNS level. We describe a case of a 52-year-old homosexual male AIDS presenting with clinically manifest tabe dorsalis. The evolution to neurosyphilis seems, at least in this stage, to be accelerated by superimposed HIV infection.