Study Type - Therapy (case series) Level of Evidence4 What's known on the subject? and What does the study add? Minimizing renal ischemia and reperfusion injury is an area of active investigation and is particularly significant in cases of laparoscopic renal surgery where the kidney experiences warm ischemia. Reports of partial clamping, early unclamping, and off-clamp laparoscopic partial nephrectomy have demonstrated potential technical modifications that can offer a protective role in preserving renal function. We investigated off-clamp laparoscopic partial nephrectomy for tumours with varying clinical stage to determine feasibility, perioperative outcomes, and renal functional changes when compared to a contemporary cohort of standard laparoscopic partial nephrectomy with complete hilar clamping performed by a single surgeon. OBJECTIVE: • To compare the operative outcomes and oncological efficacy of off-clamp (OC) laparoscopic partial nephrectomy (LPN) vs complete hilar control (HC) LPN for stage T1a-T2 renal cell carcinoma. METHODS: • Retrospective review of all LPNs between June 2006 and March 2010 was performed, stratifying 390 patients by clinical T stage (cT1a = 313, cT1b = 62, cT2 = 15). • Perioperative and postoperative parameters were analysed comparing patients who underwent OC LPN (n= 126) with those who had HC LPN (n= 264) collectively and within each clinical stage cohort. RESULTS: • There was no significant difference in the proportion of OC LPN for cT1a tumours compared with cT1b and cT2, P= 0.21. • OC vs HC LPN patients had a greater estimated blood loss (EBL) but with no significant difference in perioperative blood transfusion rates. • When compared by clinical stage, EBL was greater only for clinical stage T1a disease (P= 0.02) but not cT1b (P= 0.91) or cT2 (P= 0.42) tumours. • There was no difference in the operative time or length of hospitalization between OC and HC LPN by stage: cT1a (P= 0.77 and P= 0.17), cT1b (P= 0.77 and P= 0.07) and cT2 (P= 0.42 and P= 0.66), respectively. • In our series, one case (0.3%) of HC LPN had a positive margin on final pathology, one case was converted to open partial nephrectomy (0.3%), and two cases of OC LPN (1.6%) were intraoperatively converted to HC LPN. CONCLUSIONS: • OC LPN is a feasible surgical option for patients with cT1-T2 renal cell carcinoma that completely avoids renal ischaemic injury with the benefits of minimally invasive surgery. • LPN can be performed OC in patients with larger, more complex renal tumours without compromising the operative time, blood loss requiring transfusions, length of hospitalization, complication rates, or positive surgical margin rates compared with HC LPN. © 2011 THE AUTHORS. BJU INTERNATIONAL © 2011 BJU INTERNATIONAL.