Intra-abdominal infections are a common cause of nosocomial sepsis and are associated with a severe morbility, mortality and sanitary economy implications, especially for decentrated sanitary structures. Mortality due to diffuse suppurative peritonitis (from 10 to 20%) nowadays continues to be unacceptably high. Patients outcome is significatively influenced by early adequate surgery and/or peritoneal drainage: moreover, even early and adequate empiric antimicrobial therapy influences patients morbidity and mortality. Multiple empirical regimens have been proposed, but rarely supported by reliable randomized-controlled studies. The authors report 201 cases of patients with fever and meaningful peritoneal involvement occurred since August 1999 up to August 2005: 110 cases were conservatively treated, 91 cases were surgically treated. The paper summarizes IDAB (Infection Disease Advisory Board) guidelines inheriting management of intra-abdominal infections: empiric antimicrobial therapy for the most common causes of abdominal infections is proposed for low-mid level risk patients, focusing on antibiotic treatment duration. High risk patients need to be evaluated paying particular attention to timely surgical infection source control. CONCLUSION: Despite of the progress in antimicrobial agents and intensive care treatment, peritonitis is still one of the most important infectious problems that a surgeon has to face.