fa Mathematical Modeling and Applications of OR Mathematical Modeling and Applications of OR پژوهشی Original <em>Nowadays, manufacturers need to satisfy consumer demands in order to compete in the real world. This requires the efficient operation of supply chain planning. On the other hand, increasing worldwide environmental, lack of food resources and social concerns are motivating manufacturers and consumers to implement recycling strategies such as product recovery, waste management, or usage of recycled materials. In this study, the closed-loop supply chain network has been proposed which consists of four echelons (suppliers, plants, distribution centers, and customers) in the forward chain and three echelons (collection centers, inspection centers, and disposal centers) in the backward chain. We present a multi-product and multi-period mixed-integer linear programming problem in this paper. The objective of this study is to maximize the profit in the closed-loop supply chain network. The proposed model is applied to an illustrative example based on inspiration from the dairy industry in Iran. The solution of the proposed model is achieved by using Gams software. The results give important insight for fostering the decision making process.</em> Close-loop supply chain, mixed-integer linear programming, Network design, Dairy industry. 85 101 http://iors.ir/journal/browse.php?a_code=A-10-1422-11&slc_lang=fa&sid=1 Masoud Alinezahd مسعود علی نژاد m.alinezhad.ie@gmail.com 1111111111 1111111111 Yes Mazandaran University of Science and Technology دانشگاه علوم و فنون مازندران