Introduction. Kidney malformations are commonly identified in the antenatal period and account for 20-30% of all detectable anomalies. Both renal dysplasia and renal hypoplasia account for a significant proportion of chronic kidney disease (CKD) in children. Currently, their appearance is attributed to environmental factors in 10%, genetic and chromosome factors - 10%, and in 40-60% remain idiopathic. The disease may lead to glomerular hyperfiltration associated with hypertension, proteinuria and, in the long term, with chronic kidney failure. Material and methods. Presentation of a clinical case of late diagnosed renal hypoplasia associated with CKD. Results. 14-year-old male patient admitted to the Nephrology Department of Mother and Child Institute. On physical examination it was found pale, dry skin, with suborbital circles, reduced turgor and elasticity of the skin, obesity (BMI30.0), high blood pressure – 135/90 mm/Hg (99th percentile). Laboratory test results showed hypercholesterolaemia -7.05mmol/L, blood urea -6,6 mmol/l, creatinine -0,098 mmol/l, glomerular filtration rate (GFR)-77ml/min/1.73m2. Urinalysis showed leucocites 20-22 f/w. The imagistic exam with ultrasound detected small size of the left kidney (68x40 mm), the cortico-medullary layer 12 mm, with the pyelocalic structures deformed. Intravenous urography confirmed the small aspect of the left kidney, slightly rotated, without viewing the ureter and the function of concentration and evacuation slightly slowed. Subsequently evaluated by renal scintigraphy, was established a reduction of the function with 20% of the hypoplastic kidney. Conclusion. Children with unilateral kidney dysplasia have a higher risk for progression of CKD. The follow-up visits should include a physical exam, blood pressure measurement, proteinuria/ albuminuria screening and a sonographic assessment of the kidney.