Five cases are reviewed in which intra-abdominal pressures were used to decide whether critically ill patients would undergo exploratory laparotomy. This is a retrospective case series of a convenience sample of five critically ill, postoperative patients with a variety of underlying illnesses admitted to a surgical intensive care unit in a university hospital. Intra-abdominal compartment pressures were measured using the indirect method of urinary bladder pressure. In patients with signs of abdominal compartment syndrome, intra-abdominal pressures were measured. The pressures were measured every 6 hours until the signs had resolved or the patient was taken for exploratory laparotomy. All patients had Foley catheters. The drainage tubing to the catheters was clamped after the infusion of 200 cc of sterile water. An 18-gauge needle was inserted into the sampling port of the drainage tubing proximal to the clamp, and the needle was connected to a pressure transducer. An elevated abdominal compartment pressure was considered at greater than 25 mm Hg. The case series were reviewed to determine in critically ill patients whether intra-abdominal pressures could assist in deciding which patients required emergent exploratory laparotomy. The patients underwent frequent venous and arterial blood gas and hemodynamic measurements. If the clinical course of the patients worsened as indicated by requiring additional pressors, ventilator support and/or oliguria intra-abdominal pressures were measured every 6 hours. The five patients whose intra-abdominal pressures were elevated were taken for exploratory laparotomy. Four patients were found to have urgent surgical conditions. Intra-abdominal pressures can be used to help decide which patients can be aggressively supported and observed and which patients need re-exploration. At exploration the patient may be found to have necrotic large or small intestines instead of the classical abdominal compartment syndrome findings of ascites, hematoma, and bowel wall edema. In symptomatic patients with abdominal compartment pressures greater than 30 mm Hg, the patient should be taken for exploration. It is not necessary to perform any further diagnostic tests before exploring the patient.