A 55-year-old man presented with a painless destruction of multiple joints and neurologic deficits. He was admitted with a painless pyogenic arthritis of the right ankle. Four years earlier, he had experienced instability of the right knee after an inexplicable, progressive but painless destruction of the joint. Radiographs showed erosive changes at the smaller joints of both hands and the left foot, as well as deformation and destruction of the right foot. Results from both treponemal and nontreponemal serologic test were positive in blood. The Treponema pallidum particle agglutination index was positive in the cerebrospinal fluid. Tabetic arthropathy was diagnosed.Tabetic arthropathy is a manifestation of neurosyphilis. Because syphilis is known as "the great imitator" and tertiary syphilis is rare, recognizing the disease is the biggest challenge for health care providers. Symptoms may mimic any other disease, and many different medical specialists may be faced with these patients, or as Sir William Osler put it: "He who knows syphilis, knows medicine." Initial diagnosis is usually made on serum and cerebrospinal fluid examination. Penicillin is an effective treatment for neurosyphilis to stop progression of neurologic damage, but it does not cure the previously developed tabetic arthropathy. This case is reported to raise awareness of this uncommon but important manifestation of tertiary syphilis. Unfamiliarity with the clinical presentation of tabetic arthropathy may lead to considerable delay in diagnosis.