Segmental renal infarction (SRI) is a rare condition that causes renovascular hypertension (RVH), which accounts for 8-10% of all causes of pediatric hypertension. We report the clinical course of two children with idiopathic SRI who suffered severe arterial hypertension associated with hyponatremia. Hypertension was diagnosed during the study of hematuria in the first case and due to a hypertensive emergency in the second case. The etiology was found to be renovascular in both patients, involving the occlusion of small renal arteries and causing SRI. Our first patient was treated with partial nephrectomy, and the second patient was treated with antihypertensive medication given the impossibility of removing the infarcted renal area. The occlusion of small renal arteries is a rare disease of unknown origin in which the gold standard for diagnosis is selective renal arteriography. The definitive treatment is surgical segmentectomy. If segmentectomy is not feasible because of the localization of the infarcted area, as in our second patient, medical treatment is required. In view of the importance of RVH in children and the rareness of the particular etiology here reported (SRI), a review of the literature was done.