Sepsis is the systemic response to severe infection in critically ill patients. Sepsis, septic syndrome & septic shock represent the increasingly severe stages of the same disease. Despite the remarkable improvements in outcome, sepsis & septic shock remain an important cause of morbidity & mortality in children. This is a retrospective study among the patients who were admitted in the pediatric intensive care unit (PICU) of Children's Hospital Medical Center from Farvardin 1371 till Esfand 1375. During this period 4018 children were admitted in the PICU, 138 of these patients (3.4%) had the initial diagnosis of sepsis or septic shock. The age of these patients were from 3 months to 14 years (mean of 23.5 months). The male to female ratio was 2.1:1. Out of these 138 patients only 16 cases (11.6%) had sepsis and the others (88.4%) had criterias of severe sepsis or septic shock. Multiple Organ Dysfunction (MOD) were found in 96 cases (69.3%). Diarrhea was the most common primary disease that resulted in sepsis or septic shock. Only 20.3% of the cultures were positive, among which E-Coli was the most in 8.7%, Staphylococcus aureus in 5.7%, Klebsiella in 2.9% and pseudomonas in 1.4%. 66.7% of these patients expired, the mortality rates of the patients with severe sepsis or septic shock that concommitantely had MOD were higher than the other (P<0.0005). So it may be better if children with clinical diagnosis of sepsis be hospitalized in an intensive care unit or at minimum in a facility that can closely monitor these patients during the initial stabilization period.