A 9-year-old Haitian girl presented initially with monocular blindness and an isolated temporal arteritis, confirmed by angiographic studies and temporal artery biopsy findings. CT and MR studies of the intracranial circulation showed only an enlarged, dense superficial temporal artery. Systemic workup revealed a mildly elevated erythrocyte sedimentation rate, mild changes in white and red blood cells, and a remote history of sensorineural hearing loss. Pathologic examination of the biopsy specimen narrowed the differential diagnosis to giant cell temporal arteritis and polyarteritis nodosa. Treatment with corticosteroids alone failed, and the child returned 1 month later with severe systemic illness and encephalopathy. MR studies showed multiple cortical and subcortical foci of increased T2 signal, and gyriform enhancement on T1-weighted images. Renal and mesenteric arteriograms showed innumerable tiny aneurysms at branch points in small and medium-sized vessels, typical of polyarteritis nodosa. We found no previous reports of this initial presentation in the pediatric population for either polyarteritis nodosa or giant cell temporal arteritis.