We present the case of a 4-year-old girl diagnosed with secondary hypertension due to renal scarring. The patient was admitted to the Nephrology Clinic following an incidental finding of significantly elevated blood pressure (max. 203/136 mm Hg). Although there was no prior record of blood pressure measurements, the patient had reported occasional nosebleeds and abdominal pain. Diagnostic workup revealed elevated renin levels. Abdominal ultrasound showed kidney asymmetry and an irregular contour of the left kidney. Computed tomography angiography revealed no renal artery stenosis, but it showed multiple parenchymal narrowings in the left kidney, indicative of post-inflammatory scarring. Static scintigraphy confirmed these findings, showing impaired left kidney function (effective renal plasma flow – 20%). Furthermore, echocardiography revealed left ventricular hypertrophy. Blood pressure was normalised and clinical improvement was observed following combined antihypertensive therapy. This case underscores the importance of early diagnosis and regular blood pressure monitoring in children to prevent organ complications.