The paper deals with Aristotle’s concept of corruption. First, it reconstructs Aristotle’s debate with the pre-Socratics and then it focuses on the candidates for entity that can perish: form, matter, and substance. The text argues against the widely accepted thesis according to which substance is a corruptio simpliciter without further ado. The paper intensely relies upon ancient and medieval commentators of Aristotle. Finally, special attention is devoted to the dimension of time and the problem of actuality.