Objectives: The advancement in sepsis management has increased the survivals of patients. However, severe sepsis and septic shock patients still have high mortality. the authors intend to verify the use of the procalcitonin (pen level as a prognosis marker in the patients with severe sepsis or septic shock. Methods: 31 patients, with severe sepsis (20 patients) and septic shock (11 patients), were enrolled in the study. the authors used the mortality in Intensive Care Unit days as a prognosis index, and compared the PCT level in survivors with non-survivors, sepsis with severe sepsis and septic shock. the authors used the simplified acute physiology score 3 SAPS 3 to assess the severity of the patients and analyzed whether or not the PCT level correlated with the severity index. Results: The PCT level in septic shock patients (11.5 + or- 6,4 ng/ml) was not different from that of severe sepsis patients (8.2 + or- 4.8 ng/ml) (p 0.05). However, there was significant PCT level difference between survivors (8.3 + or- 3.7 ng/ml) and non-survivors (13.6 + or- 5.0 ng/ml) (p0.01), similar to SAPS 3. Conclusions: PCT was a prognosis marker in severe sepsis and septic shock patients like SAPS 3.