Kant’s theory of biology in the Critique of the Power of Judgment may be rejected as obsolete and attacked from two opposite perspectives. In light of recent advances in biology one can claim contra Kant, on the one hand, that biological phenomena, which Kant held could only be explicated with the help of teleological principles, can in fact be explained in an entirely mechanical manner, or on the other, that despite the irreducibility of biology to physico-mechanical explanations, it is nonetheless proper science. I argue in response that Kant’s analysis of organisms is by no means obsolete. It reveals biology’s uniqueness in much the same way as several current theorists do. It brings to the fore the unique purposive characteristics of living phenomena, which are encapsulated in Kant’s concept of “natural end” and which must be explicated in natural terms in order for biology to become a science. I maintain that Kant’s reluctance to consider biology proper science is not a consequence of his critical philosophy but rather of his inability to complete this task. Kant lacked an appropriate theoretical framework, such as provided later by modern biology, which would enable the integration of the unique features of biology in an empirical system. Nevertheless, as I show in this paper, the conceptual problems with which Kant struggled attest more to the relevance and depth of his insights than to the shortcomings of his view. His contribution to the biological thought consists in insisting on an empirical approach to biology and in providing the essential philosophical underpinning of the autonomous status of biology.