McCune-Albright syndrome is characterized by café-au-lait spot, multiple endocrine hyperfunction, and polyostotic fibrous dysplasia. A somatic point mutation of Gsalpha protein leads to an increase in the Gsalpha-associated hormone activity in McCune-Albright syndrome. Because cyclic adenosine 3',5'-monophosphate stimulates the dopamine beta hydroxylase gene, an activating mutation of the Gsalpha protein may cause the hyperproduction of norepinephrine via dopamine. We report on a 9-year-old girl with McCune-Albright syndrome complicated by severe arterial hypertension. The urinary excretion of norepinephrine was 5- to 10-fold higher than in age-matched controls. Meta-iodobenzylguanidine scintigraphy and positron emission tomography/computed tomography (PET/CT) revealed no hot spots. These findings suggest that severe hypertension might be due to an activating mutation of Gsalpha protein in sympathetic ganglia. Because of the reported association of GNAS1 gene polymorphism with hypertension, our patient provides further evidence for a role of Gsalpha protein in hypertension.