This paper presents a deterministic inventory model for perishable items when the demand has been considered to be stock and time dependent. Shortages are allowed and are partially backlogged for the model. The deterioration rate has been considered here to be constant. The objective is to determine the optimal ordering policy by finding the optimal length of the inventory interval with positive inventory and the optimal length of order cycle for minimizing the cost. The model is solved analytically and graphically by minimizing the total inventory cost. The result is illustrated with the help of numerical example of the model. Sensitivity analysis is performed to show the effect of changes in the parameters on the optimum solution. The analysis of the model shows that the solution of the model is quite stable and can be applied for optimizing the total inventory cost of perishable items in inventory for the business enterprises. © 2015, The Society for Reliability Engineering, Quality and Operations Management (SREQOM), India and The Division of Operation and Maintenance, Lulea University of Technology, Sweden.