Even the most cursory foray into business ethics will bring one face to face withKantianism. Indeed Kant’s influence on that branch of ethical theory known as deontology is so strong that some writers simply refer to deontology as Kantianism. Despite the fact that Kant’s name is often invoked in business ethics, as of 1997 there was no published book that systematically applied Kantian theory to business. (However, Bowie (1999) fills this gap.) Kant is best known for defending a version of the “respect for persons” principle which implies that any business practice that puts money on a par with people is immoral, but there is much more to a Kantian approach to business ethics than this. In this essay, I focus on five key aspects of Kant’s moral philosophy. I begin by showing some of the implications of Kant’s three formulations of the fundamental principle of ethics. I then show why Kant’s emphasis on the purity of our intentions in acting morally has created problems for a Kantian theory of business ethics. I conclude with a brief discussion of Kant’s cosmopolitan and optimistic outlook, and show the relevance of those ideas to contemporary business practice.