<bold>The aim of the study</bold> was to assess the usefulness of prognostic scales: ASA (American Society of Anesthesiologist), MPI (Meinheim Peritonitis Index), MOFS (the Multiple Organ Failure Score) and SPI (the Simple Prognostic Index) in the prognosis of the course of disease in patients operated on for peritonitis.
<bold>Material and methods.</bold> The study was conducted in the Clinical Department of General and Oncological Surgery of the Medical University in Łódź between January 2009 to December 2010. During this period 263 patients were operated on for peritonitis. Before surgery all patients were classifed into particular groups according to the above mentioned prognostic scales according to their criteria.
<bold>Results.</bold> There were 29 (11%) deaths. ASA ≥4 (p<0.0001), MPI >30 (p<0.0001) MOFS ≥2 (p<0.0001), SPI II, III, IV (p<0.0001) were important risk factors of death.
<bold>Conclusions.</bold> 1. ASA, MPI, MOFS and SPI scales are of high signifcance in predicting the outcome in patients operated on for peritonitis. 2. The ASA scale in spite and due to its simplicity is adequate enough to be used in everyday practice in patients operated on for peritonitis. 3. The MPI scale is most suitable in the scientifc aims and in comparing the outcomes of patients operated on for peritonitis.