Preserving kidney function during removal of a kidney tumor is becoming increasingly important as rates of chronic kidney disease increase. A novel modifiable factor (suture closure of the defect caused by tumor removal) was discovered on retrospective studies to account for nearly two-thirds of the 15% volume loss commonly seen in operated kidneys. We hypothesize that a randomized controlled surgical trial will show that omitting the suture closure both preserves renal function and will not lead to unreasonable postoperative complications.