The empiric antibiotic therapy can result in antibiotic overuse, development of bacterial resistance and increasing costs in critically ill patients. The aim of the present study was to evaluate the effect of procalcitonin (PCT) guide treatment on antibiotic use and clinical outcomes of patients admitted to intensive care unit (ICU) with systemic inflammatory response syndrome (SIRS). A total of 60 patients were enrolled in this study and randomly divided into two groups, cases that underwent antibiotic treatment based on serum level of PCT as PCT group (n=30) and patients who undergoing antibiotic empiric therapy as control group (n=30). Our primary endpoint was the use of antibiotic treatment. Additional endpoints were changed in clinical status and early mortality. Antibiotics use was lower in PCT group compared to control group (P=0.03). Current data showed that difference in SOFA score from the first day to the second day after admitting patients in ICU did not significantly differ (P=0.88). Patients in PCT group had a significantly shorter median ICU stay, four days versus six days (P=0.01). However, hospital stay was not statistically significant different between two groups, 20 days versus 22 days (P=0.23). Early mortality was similar between two groups. PCT guidance administers antibiotics reduce antibiotics exposure and length of ICU stay, and we found no differences in clinical outcomes and early mortality rates between the two studied groups.