We present a model for the design of multiproduct batch plants extended with parallel production lines. e proposed model serves as a basis for strategic capacity decisions and is formulated as a MILP model. First, we introduce the concept of parallel production lines into existing plant design models and optimise the assignment of products to these lines, together with the number and size of the equipment, by minimising, at rst, only capital costs. Furthermore, we focus on the mutual in uence between the design and the objective function.is objective function is not only de ned as the minimisation of capital costs, but is extended with setup and operating costs.e applicability of our model is illustrated with an example, where we compare the traditional single line design model with our introduced parallel lines model. We nd that the presence of parallel production lines is bene cial when setup costs are included. Moreover, the incorporation of operating costs a ects volume-wise asset utilisation per batch.