The incidence of neurosyphilis is currently rising due to an up-spike in sexual transmission of the causative pathogen Treponema pallidum. Neurosyphilis is difficult to diagnose due to its broad array of nonspecific clinical manifestations and lack of defining characteristics on magnetic resonance imaging (MRI). We report a case of neurosyphilis presenting with characteristic MRI findings of diplopia and subacute stroke syndrome, and review the literature to assist in differential diagnosis. A 37-year-old heterosexual Chinese male presented with a 2-month history of headache. Firstly, he was diagnosed with “tension-type headache” because of normal brain MRI. The patient developed vertical diplopia and slight numbness in the right partial body for the second administration to our institute. Personal history revealed a primary syphilis infection 11 months previously, which was treated with intramuscular bicillin. Subsequent brain MRI demonstrated an infarction in the left thalamus, a marked thickening and enhancement of the left oculomotor nerve, and focal meningeal enhancement. Magnetic resonance angiography (MRA) of the head showed no abnormalities. The patient received treatment with intravenous penicillin G and steroids. 3 months after discharge, brain MRI demonstrated complete resolution of the left oculomotor nerve and focal meningeal enhancement. Our case emphasizes the importance of early diagnosis and complete cure of syphilis to prevent progression and ensuing neurological damage. Standard follow-up is necessary for confirmation of adequate treatment response.