Malformations are among the main causes of renal disease in children, affecting 1% of the general population. Urinary tract infection is a common paediatric problem and vesicoureteral reflux is its most common complication. Aim: Assessing the need to perform a renal ultrasound as a screening method for malformations in young children with urinary tract infections. Material and methods: Renal ultrasounds were performed on 129 patients with urinary tract infections hospitalised during April 2016 – February 2017. The patients were aged between 0.4 months – 10 years, with an average of 3 years±2.5 months. Of these, 80 patients (62%) had a normal renal ultrasound report. Results: The most common finding was congenital hydronephrosis: grade I–II (30 patients – 61.2%), grade III–IV (7 patients – 14.2%) and grade V (3 patients – 6.1%). As causes of hydronephrosis, ureteropelvic junction (UPJ) obstruction was found in 18 patients (45%), vesicoureteral reflux (VUR) in 6 patients (15%) and obstructive megaureter in 4 patients (10%). Other malformations included 3 cases of renal cystic dysplasia, 4 cases of duplicated collecting system and 2 cases of unilateral renal agenesis. Discussions: Cases of low grade hydronephrosis were monitored by ultrasound; patients with history of more than 2 infections underwent cystography/voiding urosonography (5 versus 11 cases); 10 patients benefited from superior imaging, which confirmed ultrasound findings in all cases; 10 patients (25%) required surgery. Conclusions: Renal ultrasound is important in order to establish a complete diagnosis and subsequent monitoring of these cases. Voiding urosonography is a reliable, sensitive, safe and radiation-free method of investigation of vesicoureteric reflux in children.