OBJECTIVE The risks of a high intraabdominal pressure during laparoscopy are poorly documented. These aspects were studied in a relevant nonhuman primate model, the baboon (Papio anubis, Papio cynocephalus). METHODS The animals used were to be killed at the completion of a vaccine project. They were anesthetized and intubated but allowed to breathe spontaneously. In group 1 (n = 10) a fixed intraabdominal pressure (between 10 and 35 cm H2O [7 and 26 mm Hg]) was applied over 30 minutes. In group 2 (n = 7) the intraabdominal pressure was increased up to a maximum of 105 cm H2O (77 mm Hg). Blood vessels of the parietal peritoneum and omentum were systematically opened from 30 cm H2O (22 mm Hg) onward. Respiration and pulse rate were measured regularly, and the degree of respiratory distress was assessed. After death of the baboons a necropsy was carried out immediately to study the degree of lung atelectasis. RESULTS In group 1 the respiration rate increased and the heart rate decreased. At an intraabdominal pressure of > or = 30 cm H2O (22 mm Hg) moderate respiratory distress was seen after 20 minutes. In group 2 one animal had a bilateral pneumothorax at a pressure of 60 cm H2O (44 mm Hg) and died at 90 cm H2O (66 mm Hg). Severe respiratory distress was observed in the other six animals. Severe lung atelectasis was present in only one of the five primates with moderate respiratory distress of group 1 and in all baboons of group 2. CONCLUSIONS An increase of intraabdominal pressure up to 105 cm H2O (77 mm Hg) combined with intraabdominal blood vessel injury is not lethal in most baboons.