OBJECTIVES: Diabetic foot infection is a frequent complication for diabetes patients that lead to high economical costs. The purpose of this study was to develop an economic model in order to evaluate the cost-effectiveness ratios between ertapenem and the patterns of antibiotics routinely used for the treatment of diabetic foot infections at the Social Security Mexican Institute (IMSS) from the health care payer's perspective. METHODS: A cost-effectiveness analysis was developed using a Bayesian decision-tree model. The model simulates costs and effectiveness outcomes in a 4-week period. The comparators were: ertapenem(1 g daily); metronidazole(500 mg every 8 h)/ceftriaxone (1 g every 12 h); metronidazole(500 mg every 8 h)/levofloxacin(500 mg every 12 h); metronidazole(500 mg every 8 h)/ciprofloxacin (500 mg every 12 h). Resource use and cost data were obtained from hospital (second level) records of 104 of treated patients. Effectiveness measures were the percentage of clinical success without adverse events (AE) at the end of the follow-up-period. Effectiveness data and transition probabilities were taken from international published literature and were adjusted according to the antimicrobial susceptibility identified locally. The model was calibrated according to international pharmacoeconomics guidelines. One-way and probabilistic sensitivity analyses were performed using Monte Carlo Simulation second-order approach. RESULTS: Patients who received ertapenem experienced 62.7% of clinical success without AE, followed by metronidazole/ceftriaxone (23.9%) and metronidazole/levofloxacin (17.8%). Mean cost per patient were lower for ertapenem (US$4306.46) followed by metronidazole/ceftriaxone(US$8014.93) and metronidazole/levofloxacin (US$8625.11). Based on ICER's ertapenem resulted as the dominant therapy. Acceptability curves showed ertapenem as the most cost-effective therapy closer to 100% independently of IMSS willingness to pay. CONCLUSIONS: The results show that in México, ertapenem is the most cost-effective antibiotic therapy for diabetic foot infections. These results should be taken into account by Mexican decision makers for the management of this complication in patients with Diabetes Mellitus.