This paper focused on a buyer-supplier coordination model to improve deliveries in a manufacturing supply chain. The proposed model based on the integrated total relevant costs of both buyer and supplier and determines optimal order quantity, the number of deliveries/setups, and quantity of deliveries over a finite planning horizon in a relatively simple JIT (single buyer single supplier) with multiple products scenario and under deterministic conditions. It will be shown that the use of JIT purchasing reduces relevant logistics costs for both suppliers and buyers and the optimal delivery policy adopted by both buyer and supplier in a cooperative manner can be economically beneficial to both parties