Background and purpose: Laparoscopic partial nephrectomy has been one of the surgery options for patients with single renal carcinoma of T1 stage. Under the effect of some factors

intraoperative renal blood flow clamping somtimes exceeds the safe limit of 30 minutes of warm ischemia time (WIT) for renal tissues

that might results in warm ischemia-reperfusion injury to severe extent. However

there still remains controversy about the depth of this warm ischemia-reperfusion injury. So this study aimed to evaluate the effects of longer WIT on ipsilateral residual renal tissues. Methods: Forty-four patients underwent retroperitoneal laparoscopic partial nephrectomy from Jan. 2012 to Jan. 2014. All of them were divided into observe group (WIT30 min) and control group (WIT≤30 min). The differences of glomerular filtration rate (GFR) of operative kidney Pre- and post-operatively between two groups were analyzed. Results: The pre- and post-operative GFRs of operative kidney in observe group were 29.3-53.0 mL/min[(33.1±5.2) mL/min]

23.1-40.5 mL/min[(27.3±5.9) mL/min] respectively (P=0.054). The preand post-operative GFRs of operative kidney in control group were 27.4-49.6 mL/min[(32.3±4.1) mL/min]

23.8-44.4 mL/min[(29.1±5.0) mL/min]

respectively (P=0.07). There was no statistically differences of the depth of the decrease of GFRs after surgery between the two groups (P=0.051). Conclusion: WIT of 30-60 min does not result in statistically significant injury for ipsilateral residual renal function. However

it is still necessary to reserve more ipsilateral residual renal function through minimizing WIT under the premise of ensuring the safety of surgery.