Syphilis has once again become a public health issue with the advent of human immunodeficiency virus (HIV) infection. We report a 28-year-old Chinese man with recently acquired HIV infection together with early neurosyphilis. His presentation of acute mononucleosis-like syndrome, lymphadenopathy, aseptic meningitis, positive central nervous syndrome and reactive Venereal Disease Research Laboratory test in his cerebrospinal fluid helped to reach the diagnosis. Paired serum Western blot tests for HIV infection performed 1 month apart revealed either a new appearance or an increasing intensity of bands for p17, p24, p31, gp41, p52, p55, p68, gp120 and gp160 suggesting recently acquired HIV infection. The lymphadenopathy disappeared spontaneously and the neurosyphilis responded well to 14 days of penicillin G therapy. The Western blot pattern, clinical course, laboratory data, and therapeutic response indicated that the acute retroviral syndrome and early central nervous system involvement caused by Treponema pallidum occurred concomitantly.