Making an analysis of those exposed, connected with the diagnoses of day 1 (preoperatively), days 3 and 7 (postoperatively), we have noticed that the diagnostic value of IL–6 and TNF alpha for sustaining the severity diagnoses, suited the period in which the dosage has been made (peritonitis with systemic inflammatory response syndrome with or without septic complications). The gene discussed is TNF; the disease is peritonitis.