To analyze the clinical characteristic and prognosis of anti-GQ1b antibody syndrome manifested by isolated unilateral mydriasis. Methods: A case of anti-GQ1b antibody clinically manifested by acute isolated unilateral mydriasis associated with intracranial lesions was reported and the relevant literature was reviewed in this study. Results: We report a 40-year-old Chinese woman presenting with postinfectious unilateral mydriasis and blurred vision. Pupillary light reflex was decreased in the right pupil and normal in the left; ocular movements were unrestricted bilaterally. Also, brain magnetic resonance imaging revealed abnormal signals in the left hippocampus and thalamus, and somatosensory evoked potential central conduction times were prolonged in both lower limbs. Serum assay for antiganglioside antibodies revealed elevated titers for IgM anti-GQ1b antibody. The patient was treated with intravenous immunoglobulin and recovered gradually. Seven cases of anti-GQ1b antibody syndrome manifested by isolated internal ophthalmoplegia were identified from the Pubmed. Pupillary light reflex was decreased in 6 cases; weakened tendinous reflect was found in 5 cases; ataxia was identified in 3 cases; 7 cases were serum IgG anti-GQ1b antibody positive. All the cases recovered completely and had better prognosis. Con? clusion: Isolated internal ophthalmoplegia is rarely reported in anti-GQ1b antibody syndrome. Our case report helps increase the level of diagnosis and treatment of this disease.