A 69-year-old man was admitted to the Department of Ophthalmology with bilateral loss of vision. For a few months he had also had shooting pains in both legs and instability of gait. Neurological examination showed loss of vision bilaterally and minor sensory disturbances of the legs with diminished tendon reflexes. As extensive further examination showed no specific abnormalities, the tentative diagnosis 'arteriitis temporalis' was made. Despite treatment with corticosteroids his condition deteriorated. Only after a repeat medical history had been taken did it become clear that in the past he had had homosexual contact with a number of partners. This increased the likelihood of a sexually transmitted disease in the differential diagnosis. In the meantime the results from serological tests became known: there were strongly elevated titres for syphilis in both serum and cerebral spinal fluid. Eventually the patient was diagnosed with neurosyphilis with ocular involvement and tabes dorsalis. He recovered almost completely in a few months after treatment with doxycycline.