To determine the effects of carbon dioxide insufflation on renal function in a pneumoretroperitoneum model, 24 adult New Zealand rabbits were divided into four groups, six rabbits in each, The first group underwent a 2-hour CO2 insufflation at a pressure of 10 mm Hg in the retroperitoneal space after balloon dissection. In another group, the same procedure was maintained for 4 hours. In the sham-treated groups, the procedure was similarly carried out but without CO2 insufflation, In all our groups, serum and urine creatinine concentrations and renal artery and renal vein blood flow rates were determined separately at the beginning and at the end of the procedure and at 24 hours. Urine output was also recorded at the end of the procedure and at 24 hours, The serum creatinine in the 2- and 4-hour study groups had increased significantly at the end of the procedure, accompanied by a significant decrease in the urine creatinine value. Renal artery and renal vein blood flow rates and urine output were reduced in both groups during the study. All changes in the serum and urine creatinine, renal artery and vein flow rates, and urine output was more pronounced in the 4-hour group. All measures returned to their prestudy values by 24 hours. Pneumoretroperitoneum causes reversible renal dysfunction, which becomes more pronounced with prolonged insufflation, Further research is needed to show the impact of our findings in high-risk patients undergoing retroperitoneoscopic surgery.