The aim of this work is to propose a mathematical programming model for the economic lot scheduling problem (ELSP) with performance decay. First, the problem is formulated as a mixed integer nonlinear program (MINLP), which is found to be nonconvex. The model is then transformed into a mixed integer linear programming (MILP) model through the discretization of the cycle time. This model is tested in a wide set of randomly generated problems with various degrees of difficulty. The results show that the MILP model can achieve the optimum within satisfactory CPU times. An illustrative example demonstrates the applicability of the MILP model and its potential benefits in comparison with a hierarchical approach.