A (Ti,Si) inventory policy model for deteriorating items is presented in this paper. The model is developed based on the assumptions that (1) demand rate is deterministic and linearly changes with time, (2) deterioration rate is constant, (3) planning horizon is finite and known, and (4) replenishment periods are not equal. The model is solved using a dynamic programming method. The result is applicable to the case where the demand is either increasing or decreasing. A numerical example is provided to illustrate the model and solution procedure.