OBJECTIVES: : Several clinical trials have demonstrated that the supplementation of Dipeptiven® in critically ill patients in Intensive Care Units (ICUs) is associated with better clinical outcomes, such as reduction of the infection rate, shortening of ICU and hospital lengths of stay (LOS), and a trend toward reduced mortality, when compared to standard TPN regimens. Aim of the study is the pharmacoeconomic evaluation of Dipeptiven vs. standard TPN in critically ill patients admitted to Italian ICUs. METHODS: : The analysis is based on a Discrete Event Simulation model that incorporates: a) baseline outcomes rates from the 2007 GIVITI report (data from 200 Italian ICUs and over 60,000 patients); b) Dipeptiven® efficacy from systematic review and meta-analysis with a Bayesian Random-Effects model of the published clinical trials; c) national cost data in the perspective of the hospital from published sources. The simulated clinical outcomes are: death rate in ICU; infection rate in ICU; death rate in general ward; hospital LOS, divided into LOS pre-ICU, LOS in ICU, and LOS in ward (post-ICU). One-way and probabilistic sensitivity analyses were performed and the cost/effectiveness acceptability curve generated. RESULTS: Dipeptiven® results more effective and less costly than standard TPN reducing mortality rate (23.55%±15.2% vs. 34.50%±2.06%), infection rate (15.91%±3.95% vs. 18.97%±3.94%), overall hospital LOS (25.47±0.26 vs. 26.00±0.27 days) and total cost per patient (23,922±3,249 vs. 24,145±€3,361). This indicates that treatment cost is completely offset by the reduction in ICU costs, and by antibiotic costs for the treatment of ICU-emergent infections.The cost/effectiveness acceptability curve shows that Dipepetiven® has an estimated 78% probability of resulting dominant and a  90% probability of resulting cost/effective if the decision maker is willing to pay up to €1500 to avoid one patient death. CONCLUSIONS: : Dipeptiven® is expected to averagely dominate standard TPN, as it results associated with better clinical and economic outcomes.