A compartment syndrome exists when increased pressure in a closed anatomic space threatens the viability of the tissue within the compartment. When this occurs in the abdominal cavity it threatens not only the function of the intra-abdominal organs, but it can have a devastating effect on distant organs as well. Recent animal and human data suggest that the adverse effects of elevated intra-abdominal pressure (IAP) can occur at lower levels than previously thought and even before the development of clinically overt abdominal compartment syndrome (ACS). The ACS is not a disease but truly a syndrome, a spectrum of symptoms and signs that can and mostly does have multiple causes. It is only recently that this condition received a heightened awareness. This article reflects the current state of knowledge on intra-abdominal pressure regarding etiology, epidemiology, diagnosis, IAP measurement, organ dysfunction, prevention and treatment.