The authors describe a case of Takayasu's arteritis in a child of only 3 years of age, emphasizing the rarity of this disease in this age group. The child was admitted to the emergency room in a post-convulsive state after a tonic-clonic seizure. After a detailed clinical examination, extensive diagnostic tests, and observation of the clinical evolution, the diagnosis was Takayasu's disease with severe cardiac and arterial involvement. The report warns pediatricians and cardiologists to awareness of the possibility of this disease in very small infants, in countries where it is underdiagnosed.