We herein report a case of neurosyphilis that presented with isolated bilateral abducens nerve palsy. A 39-year-old man was referred to our department with diplopia. He had a history of homosexual relationships and showed only bilateral abducens nerve palsy upon a neurological examination. Positive syphilis tests in the serum and cerebrospinal fluid and a contrasting effect on the abducens nerve on magnetic resonance imaging (MRI) confirmed the diagnosis of active neurosyphilis. When a patient manifests isolated abducens nerve palsy, neurosyphilis can be a differential diagnosis, although rare, and contrast-enhanced MRI may help diagnose the disease.