SIRS (systemic inflammatory response syndrome) is thought to be caused by hypercytokinemia. On the other hand, interleukin-6 (IL-6) is reported to be one of most easily measurable cytokines and we found that IL-6 blood levels on SIRS patients are above 1,500 pg/ml which is compatible to the previously reported values. Since only 6% of SIRS patients developed MOF according to our own data, we need not overestimate SIRS as a grave clinical signs. On the other hand, it is reported that cytokine-related genetic polymorphism may affect the cytokine production following insult, or may affect the development of SIRS following insult. Therefore, we must also consider genetic aspect of cytokine biology in future study.