Objectives: Secondary ureteropelvic junction (UPJ) obstruction after failure of open and laparoscopic repair may be challenging to resolve due to possible extensive fibrosis and the increased invasiveness of this procedure. Alternatively, ureteroscopic laser endopyelotomy may be a more acceptable procedure for patients and surgeons. We report our preliminary experience with ureteroscopic holmium laser endopyelotomy after open pyeloplasty failure and define the complications that arose and the results. Materials and Methods: We performed 6 retrograde endopyelotomies with a holmium laser for failed UPJ repairs following the Anderson-Hynes procedures. Patient follow-up was carried out every 3 months using sonography and renal scan, and again after 1 year using renal scan and urography. Results: Mean hospitalization was 2.1 days. Ureteroscopic laser endopyelotomy was successful in 4 cases (66.6%). In 2 patients, failure occurred at the third month of follow-up. Complications included 1 case of slight bleeding, which was resolved conservatively without the need for blood transfusion, and 2 cases of guidewire rupture. Conclusions: Secondary UPJ obstruction is more challenging to resolve by open or laparoscopic approach. Retrograde endopyelotomy gives a valid alternative thanks to its success rate and its better acceptance by patients. We consider retrograde laser endopyelotomy the approach to choose when faced with secondary UPJ obstruction after open or laparoscopic failures.