The purpose of this study was to determine the relationships among pneumoperitoneum pressure, CO2 insufflation volume, and patient height, weight, and body mass index. Forty-one male patients undergoing laparoscopic urologic procedures prospectively had a record made of the delivered volume of CO2 during insufflation to attain intraabdominal pressures of 5, 10, 15, 20, 25, and 30 mm Hg. The relationship of the delivered volume of CO2 insufflated and the intraabdominal pressure was compared statistically to the patient height, weight, and body mass index. In addition, six domestic female pigs underwent pneumoperitoneum, and the abdominal volume was calculated for intraabdominal pressures of 0, 5, 10, 15, 20, 25, and 30 mm Hg. Four different commercially available 10-mm trocars were tested for force required for placement at intraabdominal pressures of 15 and 30 mm Hg. There was a direct relationship between delivered volume of CO2 insufflated and the pneumoperitoneum pressure. There was no significant relationship between the delivered volume of CO2 insufflated at a given intraabdominal pressure and the patient height, weight, or body mass index. During insufflation, 94% of the abdominal volume is achieved by insufflating to 15 mm Hg. There is no significant difference in the force required for insertion of different ports at 15 mm vs 30 mm Hg pressure. Increasing the abdominal pressure to 30 mm Hg provides a 50% increase in the volume of CO2 insufflated vs a standard 15 mm Hg pneumoperitoneum. However, this additional volume does not significantly change the actual abdominal volume or diminish the pressure necessary to insert a trocar.