OBJECTIVES:  To assess the cost effectiveness of gMS®Pro EDSS, a test designed to identify MS patients with a high likelihood of progressing fast and in need of more aggressive treatment. METHODS:  A literature-based discrete-event simulation follows patients visiting their physicians at defined EDSS score deteriorations. At each visit, 4 therapies are considered: three less aggressive/less expensive therapies (assumed monthly cost of $2,000/patient) and a more aggressive/more expensive therapy (assumed monthly cost of $3,000/patient) associated with severe side effects.  The more agressive therapy is only considered cost effective in fast deteriorating patients. The expected cost effectiveness of each therapy was calculated using a Markov model (using EDSS scores as health states) and applying a Bayesian updating process considering the likelihood that the patient is “fast deteriorating” and/or responds to therapy. The model compares patients’ costs and quality of life when the gMS®Pro EDSS test is used vs. when it is not. The estimated sensitivity and specificity of gMS®Pro EDSS were 65.18% and 84.09%, respectively based on clinical trail results. The costs of all non-medication costs were based on Kobelt et al. RESULTS:  Using the test, in comparison to not using the test, in a MS population containing 25% of patients who progress fast results in more frequent (25.18% vs. 24.24%) and earlier (2.24 years on average) use of aggressive therapy.  The test is estimated to result in a gain of 0.11 QALY's and to be economically dominant up to a price of $2640 (cost of medication is estimated to increase by $2984 which is offset by savings of $2704 of other direct medical costs and $2920 of production losses).  CONCLUSIONS: The gMS®Pro EDSS is likely to be a cost effective addition in the identification of the optimal therapy for MS patients.