Introduction: Fibromuscular dysplasia (FMD) is res-ponsible for about 70% of cases of secondary renovas-cular hypertension in children.It may be unilateral or bilateral with varying degrees of interest in renal arte-ries, whether or not accompanied by renal hypoplasia, resulting in thickening, narrowing and dilatation of the renal arteries. Renal hypoperfusion will activate the re-nin-angiotensin-aldosteron systemfollowed by the in-creased blood pressure, which is asymptomatic in most of the cases.

Methods: From 2015 until now, in MS.Curie Hospital, presented 4 children, ages 4 to10, who were randomly diagnosed with HTA, whose etiology has been shown to be FMD of the renal artery. At the presentation, the clinical examination was unmodified, children show-ing blood pressure values between 130/80 mmHG up to 200/120 mmHg, biological investigation revealing increased values of the renin. The abdominal ultrasound found renal hypoplasia, in three of the children. Computed tomography angiography showed unilate-ral or bilateral renal artery stenosis in varying degrees, schintigraphically the kidneys were either with decrea-sed flow either silent. At the heart ultrasound, concen-tric hypetrophy of the left ventricle was seen, accom-panied, in two of the cases by dilated cardiomyopathy and moderately to severe systolic dysfunction, without congenital heart disease. Histopatology confirmed the suspicion of fibromuscular dysplasia.

Results: Complex antihypertensive therapy was started to lower the blood pressure, using the combination of α and β blockers, calcium blocker, diuretic, with difficult control of hypertension. Nephrectomy of the affected kidney was performed, with improvement in blood pressure values, but without normalization, requiring continued antihypertensive drugs therapy. One of the children, after the removal of the hypoplastic kidney, has benefited from endoluminal balloon dilatation and stent implantation at the stenosis zone of the renal ar-tery.

Conclusions: Althought fibromuscular dysplasia is a rare disease, it can lead to severe long term complicati-ons due to the possibility of damage of the normal renal artery and due to the persistance of hyperetension after nephrectomy. Therefore, these pacients should be clo-sely monitored for early detection and treatment of the evolving complication of the target organs.