This paper describes control of inventory systems with nonperishable and perishable goods. The inventory system considered is a periodic review system where system is reviewed periodically and orders issued are replenished by the supplier after some time called Lead time. The objectives expected from such a system are that the customer demand is fulfilled and the desired stock is maintained. The customer demand is considered as an uncertainty into the system and control law based on discrete sliding mode control is developed for replenishing orders. The state space model is developed and simulations are done for replenishment orders, the on hand stock and the supply to meet the demand. The results validate the required objectives.