Introduction: The pyelo-ureteral junction syndrome is defined by a dilation of the renal pelvis and the calyxes with a downstream ureter of normal caliber. It is a fairly frequent pathology often of congenital cause whose diagnosis can be ante-natal or post-natal thanks to ultrasound. The treatment is surgical especially if there are clinical manifestations. The objective of this work is to study in general the pyelo-ureteral junction syndrome in the pediatric surgery department of the Mali hospital. Material and Methods: This was a prospective study which took place at the Mali hospital from May 2018 to April 2021. This study included all patients aged 0 to 15 who were operated on for pyelo-ureteral junction. Results: During the 3-year study period, we collected 12 cases of pyelo-ureteral junction syndrome. The average age was 3 years with extremes of 20 days and 14 years. All patients had an abdominal mass accompanied by abdominal pain in 83.3% of cases. Dehydration was present in 66.66% of patients. The attack of the left kidney was predominant is 66.66% of the patients, in only one patient the expectation was bilateral. Serum creatinine was normal in all patients. Cytobacteriological examination of urine found 2 cases of Echerichia coli infections. 10 pyeloplasties and 2 nephrectomies were performed with simple postoperative course. Conclusion: The pyeloureteral junction syndrome is a frequent pathology in the literature but not very frequent in our daily practice. Most of our diagnoses are made post natally. It is not very symptomatic, mainly affecting male infants. Ultrasound and Uro scanner have a very important role in the exploration of this pathology. Open-air surgery is the technique of choice in our context.