The advent of "minimal invasive surgery" with the development of new endoscopic techniques modified many therapeutical concepts in urology as in other fields. The treatment of the ureteropelvic junction obstruction reserved in the past to open surgery can nowadays be successfully realized with endopelvic or endoureteral techniques under visual or fluoroscopic guidance. The authors present their experience with two new techniques: antegrade endopyelotomy under visual control or retrograde fluoroscopic endopyelotomy. Based on experimental and clinical studies which demonstrated the extraordinary capacity of the incised ureter to regenerate and regain a peristaltic activity, these treatments offer a cure rate nearly as high as open pyeloplasty.