The diagnosis of sepsis and the prediction of its outcome are important aims to tackle for this heterogeneous disease. There is a lack of biomarkers to aid in identification of risk groups, inclusion of patients in ongoing studies, and better differentiation of therapeutic strategies. Since the introduction of the prohormone procalcitonin (PCT), many studies have begun to focus on new prohormones.The aim of the study was to evaluate the prognostic value of pro-atrial natriuretic peptide (proANP) as a new marker of sepsis outcome.Material and methods. A cohort of 80 patients developing post-surgical sepsis was consecutively included into this study. Blood samples were obtained for analysis of proANP and determination the serum levels of sTNF-R1, TNF-α, IL-6, IL-8, IL-10, procalcitonin and neopterin. Cytokine levels were measured repeatedly until the patients discharge from the ICU.Results. 54/80 (67.5%) fulfilled the criteria for severe sepsis and 36/80 (45.0%) developed septic shock. Multiple organ failure occurred within 60/80 patients (75.0%); the overall mortality was 26/80 (32.5%). Concerning the diagnosis of sepsis, severe sepsis, or septic shock, there was no statistical difference in the proANP values. However, there was a statistical difference in the prediction of outcome in that 26 nonsurvivors had 803.5 (441.5/ 1095) pmol/L levels while the survivors level was 315.5 (187/ 594.5) pmol/L. In addition, there were no statistical significant differences between proANP and other cytokines.Conclusions. There was a significant correlation between proANP values and the outcome of critically ill patients. ProANP does not differentiate between clinical features like sepsis, severe sepsis or septic shock.