Implementing a new strategy is the perhaps most important task of any firm's top management. Lean manufacturing and the Toyota Production System refers to the development and implementation of a new strategy as Hoshin Kanri. Success in Hoshin Kanri is influenced by many factors. This study examines how vertical organizational communication in and around the Hoshin Kanri effort impacts the effort's chances of successful completion. The study researches two cases within one firm, a medium-sized manufacturer of medical devices. Each of the two cases constitutes ‘one effort of developing and implementing a new strategy using Hoshin Kanri’. The first effort was unsuccessful, and the second effort builds on the learnings from the first effort. The study develops a set of five researchable propositions that connect vertical organization communication with Hoshin Kanri implementation success. The two cases reveal that effective vertical communication has profound effects on Hoshin Kanri success. In particular, the clarity of the effort's key targets, the credibility of current baselines, a broad and early involvement of middle managers and specialists, and the use of internal process facilitators.