['To describe the drainage and functional outcome of paediatric pyeloplasty, 1 week after stent removal 7-9 weeks after pyeloplasty using diuretic renography.', 'Between 2009 and 2014, we assessed the functional and drainage outcomes according to mercaptoacetyltriglycine MAG-3 diuretic renograms from 66 children (69 kidneys) who underwent modified dismembered Anderson-Hynes pyeloplasty for pelvi-ureteric junction (PUJ) obstruction. Stents were left in place for 6-8 weeks and postoperative renal units were evaluated with MAG-3 renogram 1 week after stent removal. Surgical success was defined by improvement of drainage (half clearance time [T/2] < 20 min), stable or improved function on the postoperative MAG-3 renogram and by decreased pyelocaliceal dilatation on ultrasonography (US) at 1 year.', 'Of the 69 kidneys with a preoperative median range T/2 of 33.4 (7.6-200) min, 60 (87%) had improved drainage curves, with a median (range) T/2 of 6.9 (1.6-19) min. Thirteen percent (9/69) had persistent impaired drainage, with a median (range) T/2 of 36 (24-108) min. Of these nine children, one girl was found to have a persistent obstructive pattern (T/2 = 30 min) associated with a decreased split renal function (SRF; from 42 to 33%) and persistent hydronephrosis (at 28 mm). Redo pyeloplasty was performed 2 months after the initial procedure (and 18 days after stent removal) and renal function recovered to 47%. The remaining eight patients were free of symptoms; hydronephrosis improved at 1 year (anteroposterior diameter decreased from 28 to 18.5 mm; P = 1.94) and SRF remained stable (44.5 vs 48.5% after repair; P = nonsignificant). In the 29% of kidneys (20/69) that had preoperative impaired SRF, postoperative renal function improved in 75% (from 27.5 to 43%; P < 0.001), remained unchanged in 2% and one kidney (0.2%) deteriorated. The median (range) postoperative follow-up was 18 (12-90) months.'] Does early mercaptoacetyltriglycine ( MAG-3 ) diuretic renography result after pyeloplasty?