This case report presents the clinical record of a 37-year-old man who presented with a dense right hemiplegia, found to be caused by a left medial medullary stroke. The cause of the stroke was unclear, and bacterial endocarditis was initially suspected. However, he was ultimately found to have neurosyphilis on a background of undiagnosed human immunodeficiency virus and was treated with benzylpenicillin. This case report reviews the diagnosis of neurosyphilis and highlights the importance of considering neurosyphilis as a rare but important cause of stroke, especially given the increasing prevalence of syphilis in Australia.