PurposeTo identify the risk factors for adverse outcomes after pediatric pyeloplasty.MethodsWe conducted a retrospective review of all children under the age of 14 years who underwent primary pyeloplasty for unilateral ureteropelvic junction (UPJ) obstruction at a single teaching hospital in Tunisia between January 1, 2013, and December 31, 2022.ResultsA total of 103 patients were included. Median age of patients at surgery was 27 months (interquartile range [IQR], 13–44). On ultrasound, median renal pelvic anteroposterior diameter was 3.2 cm (IQR, 2.3–4), and the median renal cortex thickness (RCT) was 2.5 mm (IQR, 2–3.5). Median differential renal function (DRF) on preoperative radionuclide renal scan was 40% (IQR, 30–46). Postoperative adverse outcomes occurred in 28 patients (27.2%). These included 19 cases of urinary tract infections (UTIs), 11 cases of UPJ restenosis, four cases of UPJ leakage, two cases of urinoma, and two cases of diversion‐related complications. Multivariate logistic regression analysis revealed two factors significantly and independently related to postoperative negative outcomes: RCT <3 mm and DRF > 50%.ConclusionOur study demonstrated that preoperative RCT on ultrasound of less than 3 mm and preoperative DRF on radionuclide renal scan of more than 50% were independent risk factors for adverse outcomes following pediatric pyeloplasty. These factors could be of interest in identifying, early on, patients who will develop postoperative negative outcomes, giving them more attention and support, and explaining the prognosis to the patient and family.