OBJECTIVES: Increasing rates of resistance to antimicrobial therapy increase the risk of therapeutic failure and impose a challenge on therapy of infections. Thereby, resistant microorganisms lead to a significant increase in patient morbidity, mortality, and health care costs. Tigecycline, a glycylcycline, offers a broad-spectrum of activity including resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA). In order to assess the cost-effectiveness of Tigecycline vs. selected standard antibiotics, we modeled its use in the treatment of complicated intra-abdominal infections (cIAI). METHODS: A decision-analytic model was developed and adapted to estimate expected outcomes and costs of initial antibiotic therapy. Tigecycline therapy was compared with ceftriaxone/metronidazole, cipro-floxacin/metronidazole, imipenem/cilastatin and levofloxacin/metronidazole. We used published data on pathogen prevalence, in-vitro eradication rates, length of stay (LOS), failure rates and mortality in order to populate the model. Information on inpatient costs and drug costs were derived from official databases. RESULTS: Overall success rate of initial tigecycline therapy was 89%. Ceftriaxone/metronidazole (71%), ciprofloxacin/metronidazole (70%), imipenem (82%), levofloxacin/metronidazol (76%) showed lower suc-cess rates. LOS was shortest with tigecycline therapy (13.8 d vs. 15.1, 15.1, 14.3, 14.7 respectively). Cost-effectiveness of tigecycline was better than for all comparators (6631.76€ vs. 8542.42€, 9200.67€, 7251.55€ and 7925.48€ per treatment success). Tigecycline therapy was dominant, e.g. it was more ef-fective than all other regimens at lower total costs. CONCLUSION: The model indicates that empirical therapy with tigecycline is more cost-effective than standard antibiotic regimens.