Objectives: To prospectively compare a novel type of valveless trocar that creates a curtain of pressurized carbon dioxide [CO2] gas (which maintains pneumoperitoneum at a lower gas flow rate) with standard trocars; to quantify the volume of CO2 used; and to characterize CO2 elimination during laparoscopic renal surgery. Methods: A total of 51 patients undergoing laparoscopic renal surgery by a single surgeon were prospectively evaluated using either the valveless trocar (n = 26) or standard trocars (n = 25). Patient demographics, operative time, volume of CO2 gas consumed, CO2 elimination, perioperative parameters, and postoperative complications were recorded and analyzed. Results: Both patient cohorts were comparable in their preoperative demographics, including body mass index, the number of patients with chronic obstructive pulmonary disease, and smoking history. Mean operative time was lower in the valveless trocar cohort (124.1 minutes) compared with the conventional trocar group (145.6 minutes), P = .047. Use of the valveless trocar was associated with a lower volume of intraoperative CO2 consumed (120.0 ± 82.8 vs 300.6 ± 191.5; P < .001) and reduced CO2 elimination compared with standard trocar use after the first 16 minutes of insufflation (P < .05). Minimal complications occurred, including 2 cases of subcutaneous emphysema in the valveless trocar group, and 1 case of respiratory acidosis in the conventional trocar group. Conclusions: Use of a valveless trocar significantly reduced CO2 consumption during transperitoneal laparoscopy. The valveless trocar also demonstrated significantly reduced CO2 elimination and absorption when compared with the standard trocar. © 2011 Elsevier Inc.