It remains a challenging task for the paediatric urologist to differentiate between obstructive and nonobstructive hydronephrosis in children. This study aimed to evaluate the role of renal Doppler ultrasonography in diagnosing obstruction, in unilateral equivocal hydronephrosis, by measuring intrarenal resistive index in both, hydronephrotic as well as in contralateral healthy kidney and comparing the data.This prospective study was done in the Department of Radiodiagnosis of MGM Medical College & M.Y. Hospital, Indore (M. P.), from MAY-2017 to JULY-2018, in 62 patients (<16 years age),having unilateral urinary tract dilatation. In this study,PUJ obstruction was found to be the most commonly seen unilateral obstructive pathology, and VUR was the most frequent nonobstructive pathology. The mean RI, RIR and DRIvalues of hydronephrotic kidneys were significantly higher (0.82, 1.13, 0.09)in obstructive cases, than in non obstructive cases (0.77, 1.02, 0.03).The sensitivity, specificityand diagnostic accuracy of the mean RI, in our study was found to be 93.75%, 33.33 % and 64.52 % respectively, and for the RIR and DRI, 87.50%, 90.00 % and 88.70% respectively.Thus, because of its high sensitivity and specificity, the colour Doppler ultrasound study of intrarenal renal arteries, holds a unique role in imaging workup as well as in optimal management planning, in cases of unilateral paediatric hydronephrosis.