Guillain-Barré syndrome (GBS) is frequently complicated by hypertension, which has been ascribed to sympathetic nervous system hyperactivity. We report the case of a child with GBS and hypertension that appeared to be related to increased renin-angiotensin activity. Urinary catecholamine excretion was normal. Propranolol therapy successfully controlled the hypertension. Evaluation of the renin-angiotensin system and catecholamine excretion is indicated in patients with GBS and hypertension.