ChAdOx1 nCoV-19 is an effective and well-tolerated coronavirus disease 2019 vaccine. However, rare cases of serious adverse events have been reported with it. We report a patient who did not have active or prior coronavirus disease 2019 infection, who developed Guillain-Barré syndrome 7 days following the first dose of ChAdOx1 nCoV-19 vaccination. He was treated with intravenous immunoglobulin, with stabilization of the disease. Proper monitoring and prompt reporting of such cases are required to ensure the safety of the vaccine.