Purpose: Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disease that can be associated with autoimmunity, paraneoplastic tumour, infection or unknown aetiology.

Methods: We describe a 54-year-old woman who developed severe OMS, with the clinical onset occurring 2 months and 15 days after she experienced dizziness, vomiting and fever related to a herpes simplex virus infection. The patient was treated with hormones and clonazepam, and the symptoms of myoclonus and ataxia disappeared.

Results: The patient was followed up for 1 year with no recurrence of symptoms.

Conclusions: The case suggests that herpes simplex virus infection is a possible cause of OMS.