Endocrine hyperiension is a rare cause of secondary arterial hypertension within the pediatric population. An accurate diagnosis is important since many of these cases may eventually be cured. We present an 11 year old boy referred due to arterial hypertension and bilateral nephrocaloinosis. On admission appeared healthy with height of 132 cm (3rd centile), weight of 23 kg(<3rd centile) and BP:130/90(>90 centile), the rest of the physical exam was unremarkable. Lab: Blood: Sodiur: 140 mEq/L, potassium: 2.8 mEq/l, creatinine: 0.7 mg/dl, calcium 8,9 mg/dl; aldosterone: < 25 pg/ml (12-160) and Plasma Renin Activity (PRA): 0, 2 ng Ang.I/ml/h (0, 2-2, 7) without postural variations. Morning (8:00 AM) cortisol:10.4 ug/dl and normal circadian rythm; urinary free cortisol:19 ug/day. Urinary concentrations of THF, alloTHF and THE determined by gas chromatography were 0.74, 0.93 y 0.16 umol/24 hs respectively. These results were normal for age, however the ratic THF+alloTHF/THE of 10.4 is very high (normal <1.0) allowing the diagnosis of AME. This syndrome is characteryzed by arterial hypertension, hypokalemia and inhibition of aldosterone and PRA, due to an inadecuate peripheral conversion of cortisol to cortisone secondary to a defect in the 11 B HSD. The responsable gen defect in this case is under study. The patient was treated with 0.5 mg/day of dexamethasone having normalized the arterial pressure and the serum potassium.