['The surgical treatment of choice for significant hydronephrosis is dismembered pyeloplasty. While in open surgery, extensive resection of the dilated pelvis is common practice, laparoscopically usually only a sparing resection is performed. We compared the treatment results of both techniques to investigate whether extensive resection is necessary or not in dismembered pyeloplasty procedures.', 'To obtain comparable renal units, matched pairs according to age and relative kidney uptake as shown by (123)J-orthoiodohippurate renography were selected out of a total of 76 patients who underwent dismembered pyeloplasty between 2000 and 2007. Twenty-four patients complied with the criteria for inclusion in the study. Changes in urinary drainage preoperatively and at three months postoperatively were compared between both groups.', 'The mean age in the sparing resection group was 3.8 years (range 0.3 to 14 years); in the extensive resection group it was 3.4 years (range 0.5 to 10 years). Mean urinary drainage improved significantly in both groups from 35.1 +/- 10.7 % to 75.2 +/- 13.2 % (sparing resection) vs. 45.1 +/- 23.7 % to 70.2 +/- 22 % (extensive resection). There were no differences between the groups (p > 0.05).'] Is excision of the dilated pelvis necessary in laparoscopic dismembered pyeloplasty?