BACKGROUND Systemic Inflammatory Response Syndrome (SIRS) is an inflammatory condition which affects multiple systems in the body and often occurs as a response which is immunologically mediated by the protective immune system to infectious agent. Magnesium plays a vital role in sepsis and systemic inflammatory response syndrome (SIRS) The aim of this study is to estimate the serum magnesium concentrations in patients with SIRS in the medical ICU, to correlate with prognosis of SIRS patients by comparision with sequential organ failure assessment scoring and to assess the clinical outcome.