This paper aims at understanding how the pull production planning approach can be implemented in a batch-mix process business through the theory of constraints (TOC). The paper, after a brief review of the main streams of study on the TOC, identifies the key academic and managerial issues discussed about the process industries. Among these, a major one concerns production and inventory management for different types of process industries and the need for a transition towards a pull approach. Thus, a case-study is presented, concerning a batch-mix process company, which applied the TOC. The paper describes the main features of the process, as well as the key decisions and activities performed in such plant in order to lead the transition to a pull system through the implementaion of DBR.