Introduction: Transient oliguria during laparoscopic surgery is a known phenomenon. Currently, no data on the impact of pneumoperitoneum on renal function in children are available. Patients and Methods: Thirty children with normal kidney function, who underwent laparoscopic surgery, were included in a prospective study. A transure-thral catheter was placed to measure urine output during and 6 hours after operation. Renal blood flow (resistive index) was evaluated by Doppler ultrasound of a segmental renal artery before surgery, every 15 minutes during laparoscopy, and after 24 hours. Blood and urine samples were studied before and 24 hours after surgery. Hemodynamic parameters were monitored continuously during stan-dardized anesthesia, including a standardized intravenous infusion regimen. Results: Urine output decreased within 45 minutes of pneumoperitoneum in all patients. Of 8 children younger than 1 year, 7 (88% ) developed anuria vs 3 of 22 (14% ) children aged 1 to 15 years (P < .001). Nine children 1 year and older (32% ) developed oliguria. There was a significant recovering in the mean urine output until 5 to 6 hours after pneumoperitoneum in both age groups. No significant alterations of the renal blood flow (resistive index) and the serum and urine levels of cystatin C, creatinine, and urea nitrogen were evident until 24 hours postoperatively. The volume of infusion during pneumoperitoneum did not correlate with urine output. Conclusion: Pneumoperitoneum leads to anuria in most children younger than 1 year and to oliguria in about one third of older children. This is a completely reversible phenomenon. Urine output should not be taken into consideration for calculating intravenous fluid administration during pneumoperitoneum in children. Currently, no data on the impact of pneumoperitoneum on renal function in children are available. Patients and Methods: Thirty children with normal kidney function, who underwent laparoscopic surgery, were included in a prospective study. A transure-thral catheter was placed to measure urine output during and 6 hours after operation. Renal blood flow (resistive index) was evaluated by Doppler ultrasound of a segmental renal artery before surgery, every 15 minutes during laparoscopy, and after 24 hours Blood and urine samples were learned before and 24 hours after surgery. Hemodynamic parameters were monitored continuously during stan-dardized anesthesia, including a standardized intravenous infusion regimen. Of: 8 children younger than 1 year, 7 (88%) developed anuria vs 3 of 22 (14%) children aged 1 to 15 years (P <.001). Nine was 1 year and older (32%) developed oliguria. There was a significant recovering in the mean urine output until 5 to 6 hours after pneumoperitoneum in both age groups. No significant alterations of the renal blood flow (resistive index) and the serum and urine levels of cystatin C, creatinine, and urea nitrogen were evident until 24 hours postoperatively. The volume of infusion during pneumoperitoneum did not correlate with urine output. Conclusion: Pneumoperitoneum leads to an uria in most children younger than 1 year And to oliguria in about one third of older children. This is a completely reversible phenomenon. Urine output should not be taken in consideration for calculating intravenous fluid administration during pneumoperitoneum in children.