This prospective non-interventional study is aimed at evaluating the role of enterococci in the postoperative course of postoperative peritonitis (POP) and the predictive factors for isolating Enterococcus spp. All adult patients, hospitalized in intensive care, who had POP between September 2006 and February 2010 were analysed. The patients' baseline clinical characteristics and microbiological and surgical characteristics of the first episode of POP were recorded. The rates of surgical and non-surgical complications and mortality were studied. A total of 139 patients were analysed and Enterococcus spp. were recovered in 61 patients (43%). The presence of enterococci was associated with significantly more intra-abdominal abscesses (26% vs 12%, p=0.025), but did not affect the rate of reoperation or mortality. Antibiotic use before reoperation was the only independent predictive factor for isolating enterococci (OR=2.19, CI95%: 1.02-4.70, p<0.043). Although mortality was not affected by the presence of Enterococcus spp., a higher rate of intra-abdominal abscess was found, suggesting that enterococci play a significant role in postoperative peritonitis, but the need to treat them remains to be determined. Previous antibiotic use before reoperation was a key factor in predicting the subsequent recovery of enterococci.