The abdominal compartment is limited by the abdominal wall, Mm. Psoas, vertebral column, diaphragm and the pelvis. Thus the retroperitoneum is included. Elevated intraabdominal pressure may profoundly impair the function of the entire gastrointestinal tract, the cardiovascular, respiratory, and renal system. Reduction of increased intraabdominal pressure may reverse all these adverse effects. The most common causes of elevated intraabdominal pressure are abdominal operations, abdominal trauma, diffuse peritonitis, ascites and peritoneal edema following resuscitation. Excessively increased intraabdominal pressure may result in a total loss of function and may lead to death. Such a condition is called an abdominal compartment syndrome. It usually requires operative decompression. According to animal experiments and clinical experiences suggestions for treatment are given. Diagnostic suspicion of elevated intraabdominal pressure may be confirmed with objective measurements. Since bedside manometry using a Foley catheter provides a valuable estimate of intraabdominal pressure and is easy to perform, intraabdominal pressure values may contribute to medical decision making. At this time there is a great need of controlled clinical trials to point out the importance of increased intraabdominal pressure and the abdominal compartment syndrome.