OBJECTIVES: To adapt an existing and previously published economic (micro-simulation model) in HIV (ARAMIS) to evaluate the cost-effectiveness of maraviroc (MVC) in the US in treatment naïve HIV-patients based on the MERIT (Maraviroc versus Efavirenz in Treatment-Naive Patients) study. METHODS: MVC was compared to efavirenz (EFV) in treatment naïve patients with CCR5-tropic HIV. Efficacy and safety data were based on the post hoc analysis in the MERIT study in patients rescreened with an Enhanced Sensitivity Trofile Assay (ESTA). ARAMIS-MVC is a microsimulation Markov model, has a lifetime analytic time horizon with a monthly cycle length. Health states are defined in terms of chronic and acute HIV/AIDS. Treatment algorithms were updated based on guidelines and expert opinion. Long-term non-AIDS diseases (Cardiovascular, hepatic and renal diseases and non-AIDS defining cancer) were included in the model to reflect the higher prevalence of these illnesses in the HIV population and depended on age, CD4-cell count and hepatic status. Costs included antiretroviral treatment costs, HIV care, testing, adverse event (gastrointestinal events, rash, neuropsychiatric adverse events) and non-AIDS disease costs, at the 2012 level. The cohort of the model used the population included in the MERIT study and 1,000,000 simulations were used for the model. RESULTS: The ARAMIS-MVC model indicates that MVC compared to EFV over a life time is associated with some additional quality-adjusted life years (QALY) (0.092 difference) but with some additional total costs ($8,900 additional costs for MVC). The incremental cost effectiveness ratio for MVC compared to EFV is $96,000 per QALY gained. Life expectancy with MVC was slightly higher than EFV (2.7 months difference). CONCLUSIONS: MVC is a cost-effective treatment option for CCR5 tropic treatment-naïve patients in the US considering a threshold of $100,000/QALY.