Pneumoperitoneum is defined as the existence of extraluminal air in the abdominal cavity. In 80-90% of cases is due to perforation of a hollow organ. However, in 10-15% of cases, it is nonsurgical pneumoperitoneum. The case of a patient undergoing mechanical ventilation, developing abdominal compartment syndrome tension pneumoperitoneum is reported. Female, 75 years old asking for advise due to flu of long term duration. Given her respiratory instability, admission to the Intensive Care Unit is decided. It is then intubated and mechanically ventilated. Chest x-ray revealed a large pneumoperitoneum but no pneumothorax neither mediastinum; and due to the suspicion of viscera perforation with clinical instability secondary to intra-abdominal hypertension box, emergency surgery was decided. When discarded medical history as a cause of pneumoperitoneum, it is considered that ventilation is the most common cause. Benign idiopathic or nonsurgical pneumoperitoneum, can be be treated conservatively if the patient agrees. But if intraabdominal hypertension prevails, it can result in severe respiratory and hemodynamic deterioration, sometimes requiring abdominal decompression to immediately get lower abdominal pressure and thus improve hemodynamic function. Copyright © 2015 Academia Mexicana de Cirugía A.C. Published by Masson Doyma México S.A. All rights reserved.