Acute compartment syndrome (ACS) occurs when pressure within a closed space causes ischemia to the tissues within that space. It is relatively rare, with an incidence of 3.1 per 100,000, but it can be devastating if not promptly diagnosed and treated. The diagnosis of compartment syndrome is a clinical one, based primarily on the presence of pain out of proportion to the clinical situation, often worsened by muscle stretch. Based on a few case reports and case series, some, particularly in the orthopedic community, have suggested that regional anesthesia should be avoided in patients at risk for ACS. This is based on a concern that the analgesia from regional anesthesia may mask the hallmark sign of ACS, pain.