IntroductionAs acquired immunodeficiency syndrome (AIDS) becomes more widespread, there will be an increasing need for diagnostic AIDS-related neurological syndromes. AIDS-related myelitis is easy to be ignored, and AIDS-related longitudinal myelitis has not yet been reported.Case presentationA 45-year-old male patient was admitted to our hospital after 3 days of progressive slurred speech and limb weakness. Neurologic examination revealed near-complete four-limb paralysis with dyspnea, dysarthria, and neck rigidity. Contrast-enhanced T2-weighted magnetic resonance imaging showed hyperintensities within the entire spinal cord. Cerebrospinal fluid analysis showed elevated white blood cell count and protein level. He was administered high-dose immunoglobulin and methylprednisolone. There was rapid regression in his symptoms after a month of therapy.ConclusionsThis unique presentation of AIDS with longitudinal myelitis involving the entire spinal cord enriches our understanding of the clinical spectrum of this condition. Our case provides essential information for the diagnosis and treatment of longitudinal myelitis in AIDS patients.