The clinical and safety efficacy of a new wide spectrum beta-lactam agent for most pathogen intra-abdominal infection germs is evaluated herein. Its chemical name is Ertapenem (MK-0826). Its pharmacokinetic characteristics and the known antibacterial spectrum enable the potential use of one daily dose in the treatment of infections by aerobic and anaerobic bacteria. This is a sub-group of patients that have been treated within a multinational, prospective, randomized, controlled and double-blind study, to compare the safety and efficacy of ertapenem (100% vs 88%) with piperacillin/tazobactam in patients that have undergone surgery due to complicated intra-abdominal infection, from April 1998 to October 1999, pursuant to the IDSA/FDA standards. Twenty local patients were evaluated from a total of 623 patients in 17 countries. Acute perforated appendicitis was the most frequent pathology in both groups. The recovery ratio was slightly higher in the group, which was administered ertapenem, with no documented clinical failure. This study shows the efficacy of ertapenem in the treatment of intra-abdominal infections using a single 1-gr/day dose, equivalent to 3.375 gr of piperacillin/tazobactam every six hours. Tolerance and safety were similar in both groups. No side effects, or mortality cases were registered. The results of this study indicate that ertapenem might be the therapeutic option to discard the combination of antibiotics or the use of multiple doses in intra-abdominal infections.