The infection of pancreatic necrosis occurs in approximately 37% of cases and it is one of the most serious complications in severe acute pancreatitis (SAP) with up to 80% of mortality. The aim of this research is to study the microbiological spectrum in pancreatic necrosis and to analyze the association between infection of necrosis and mortality. A retrospective study was conducted during the period between January 2002 and March 2012 in the SAP Unit of Hospital Nacional Edgardo Rebagliati Martins. One hundred and fifteen patients with diagnosis by fine needle aspiration or suspicion of infection of necrosis that required necrosectomy and had an intraoperative culture were studied. The microbiological spectrum and the mortality were analyzed. From a total of 115 cases, 85 patients (74%) had a positive culture of the necrosis. Microbiological cultures were monomicrobial in 64 cases (75%). E. coli was the most common microorganism isolated in 34 cases (40%) and candida albicans was isolated in 12 cases (14%). Postoperative mortality was 15% (22 cases), from which 17 had positive cultures in the necrosis. In the group of confirmed infected necrosis, a higher mortality was found when associated with a positive blood culture (29%) rather than with a negative blood culture (6%) (odds ratio = 6.67; IC95%: 1.41-31.42, p = 0.01). Conclusions. In this series monomicrobial infection was predominant, and E coli was the microorganism most frequently associated with necrosis infection. Higher mortality is found in patients with confirmed infected necrosis when bacteremia is associated.