Based on the concept of the systemic inflammatory response syndrome (SIRS), a one year retrospective study was carried out to examine SIRS criteria as a simple and rapid predictor of outcome for emergency patients. Among a total of 2,180 patients transported to the emergency room by ambulance, 318 (14.8%) had primary SIRS and 389 (17.8%) met SIRS criteria at some point during the entire treatment period. The admission rate for primary SIRS increased sequentially as more SIRS criteria were met, rising from 15.4% in non-SIRS to 100% when all four criteria were met. The mortality of primary SIRS also increased sequentially as more SIRS criteria were met, rising from 1.4% in non-SIRS to 35.3% when all four criteria were met. Furthermore, heart rate, C-reactive protein and platelet count were considered to be potentially useful new criteria for a group of SIRS patients with a high risk of mortality (high-risk SIRS), based on a comparison of variables between SIRS patients who died and SIRS patients who survived. The mortality associated with primary SIRS increased sequentially as more high-risk SIRS criteria were met, rising from 7.6% when none were met to 50.0% when two criteria were met. Considering the high specificity of primary SIRS for admission (89.5%) and mortality (86.8%), SIRS criteria have clinical and prognostic importance in the management of emergency patients. Given the high mortality (29.9%), the new high-risk SIRS criteria may also be useful as entry criteria for clinical trials of innovative therapies for patients with SIRS.