This chapter describes the evaluation model developed to capture the underlying hypertension disease pathway and the impact of the sequential use of antihypertensive drug(s). The ultimate goal of this evaluation model is to provide the optimisation model with the value of the objective function (i.e., the long-term costs and effectiveness of a candidate sequential treatment strategy in a UK National Health Service (NHS) perspective). The underlying evaluation model is constructed with a short-term drug switching model, which has a form of successive decision tree, and a long-term CVD model, which is a standard Markov model. All the parameters and assumptions used to build the evaluation model are also provided.