In this section we obtain the bilevel production-transportation problem (BD-PTP) by introducing the hierarchy of decision making into the D-PTP. Given the D-PTP in the context of bilevel programming we consider two decision-makers placed at different hierarchical levels. The one on the upper level - the leader - has to organize the production so as to meet the demand at minimal production costs. His decision concerns production modes of the plants. Once he has made his decision, the decision maker at the lower level - the follower - has to organize the transportation of the products to the customers so as to achieve minimal transportation costs. The bilevel formulation of the BD-PTP is now as follows